9/16 - 3/20 How to Subtract Fractions Explained Step-by-Step!

Think you can solve 9/16 - 3/20? 🤔 Subtracting fractions might seem tricky, but with the right method, it's easy! In this video, we’ll break it down step-by-step and show you how to find the least common denominator (LCD), subtract properly, and simplify your answer.
📌 What You'll Learn:
✔️ How to find the least common denominator (LCD)
✔️ Step-by-step method to subtract fractions correctly
✔️ How to simplify the final answer
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[@George50809]

His method for finding the LCD is bullet proof.

[@tomtke7351]

9/16 - 3/20 16 = 2×2×2×2 20 = 2×2×5 LCD = 2×2×2×2×5 = 80 9/16 = 45/80 3/20 = 12/80 45/80 - 12/80 = 33/80

[@panlomito]

16 = 4 . 4 and 20 = 4 . 5 meaning one 4 in common and so the LCD = 4 . 4 . 5 = 80 (9 . 5 - 3 . 4) / 80 = (45 - 12) / 80 = 33/80

[@Alfredo-uc9dx]

You teach so good.

[@bertmoss7791]

Job well done.

[@mylittlepitbull3143]

I'm glad I could do it in my head even though I'm high as f***.

[@russelllomando8460]

33 / 80 LCD = 80 thanks for the fun.

[@jessemallory741]

45/80 - 12/80 = 33/80

[@faanmuller4569]

I am stunned! As an octogenarian I could figure out in seconds the correct answer by simply applying basic arithmetic we did in the 1950s. Enjoyed your video, however!

[@Meh-j9s]

It’s pretty easy to get 180/320 - 48/320 and then simplify 132/320 66/160 33/80

[@davidhair8295]

That is how I did it. I get lost in all of the prime factors. I suspect that with larger numbers, his way MIGHT be better.

[@robertlawson8572]

Yes, multiply the denominators (16x20) crossmultiply numerators and denominators (9x20, and 3x16) you get to your (180 - 48)/320, leading to 132/320, then simplify... I went to a seminar at my granddaughter's school years ago, and was taught about "modern maths methods" tedious, long winded, and a teacher will have lost the ADD / ADHD pupil contingent long before arriving at a solution... They'll have drifted off into some sort of reverie or started chewing their pencils... Once the student has done it "our" way a few times, they may, or may not realise, as a matter of course, that they can work out an LCM of 80 early on, and then the cross multiplication is not needed. 1/16 is 5 1/80ths, 1/20 is four 1/80ths, and get, within seconds, to (45-12)/80...

[@gavindeane3670]

​@@davidhair8295I think the trick is not to think of them as different methods. To add and subtract fractions we just need any convenient common denominator. One way to get a convenient common denominator here is just multiplying 20 by 16 to use 320 as the denominator. Another way might be to notice that 16 and 20 are both factors of 80, so use 80 as the denominator. With bigger and less friendly numbers, maybe the most convenient way to find a common denominator is via the prime factors approach. I think of it all as the same method: to add or subject fractions, we need a convenient common denominator. How you choose to go about identifying a common denominator is an unimportant detail. It's up to you - do it whatever way you find most convenient.

[@TonyFisher-lo8hh]

How does it arise we need a whole video on a topic taught (or always was) in about 3rd year primary school?

[@MrSummitville]

Because a every student, in every public school, in Chicago recently *FAILED* the state math exam. That's why! Because my 16 year old employee can't make change from a $20.

[@chrisdissanayake6979]

Answer: 33/80 ---------- 9/16 - 3/20 LCD: 4 x 4 x 5 = 80 45/80 - 12/80 = 33/80

[@thechards9545]

mando you waffle on. Maybe just address the problem and not draw it out by useless commentary

[@KollectingKaos]

9/16-3/20=45/80-12/80=33/80

[@georgecattani7199]

LCD= 2x2x2x2x5 =80 9 - 3 45 - 12 33 ---- = ------= --- 80 80 80

[@kranser]

Is there an advantage to using the alternate method of taking any common denominator to work with (e.g. by using D1 * D2)) for the subtraction and then simplify the fraction once you get a result? So in your example, we would get the denominator of 320 (not 80), and the calculation would be 180/320 - 48/320 = 132/320 and this would then simplify down to the same answer you got of 33/80. This way you do not need to find the lowest denominator and can skip that step...

[@gavindeane3670]

If you find it easier to do it that way then that is the advantage. Mathematically it's the same thing either way so unless you're doing a test or exam where you're asked to demonstrate your knowledge of a specific approach, then the best approach is whatever approach you feel most comfortable and confident with.

[@EricWells-s2p]

9 / 16 was fully reduced. 3 / 20 was fully reduced. The LCD/LCM was 80. 33 / 80 had to be fully reduced. There was no reason even to consider that it might not have been (fully reduced).

[@robmartin5518]

super simple remembering x - y is the same as -y + x: -3/20 + 9/16 20 * 4 is 80 and 16 * 5 is also 80 so the common denominator we need to use to add these two fractions is 80 4 * -3 is -12 and 9 * 5 is 45 so the problem becomes -12/80 + 45/80. -12 + 45 is 33 Final answer is 33/80

[@davidhair8295]

Got it. Different route but same answer.

[@gavindeane3670]

Can't add and subtract things if they're not the same kind of thing. Sixteenths and twentieths are not the same kind of thing, so we need to fix that. An obvious common multiple of 16 and 20 is 80 so we can turn both these fractions into eightieths and then they will be the same kind of thing. 9/16 is 45/80 and 3/20 is 12/80. So we have 45 eightieths and we're subtracting 12 eightieths. If you have 45 of something and you subtract 12 of them, you end up with 33 of that thing. So the answer is 33/80.

[@mariaaugustahenson4970]

33/80 is the answer

[@rodfulford4306]

33/80

[@dwaipayandattaroy9801]

33/80 HEE HEE 😂 💀✌

[@mikesheth5370]

Simple ! Start with MCD! Which is 320! 180 or 160 doesn’t work! Guess few LCd and 80 is The lowest! 60 or 40 doesn’t work!

[@narenmenon6906]

LOWEST COMMON DENOMINATOR IS 80 2 SECONDS...

[@imagseer]

In my head instantly 33/80. Not sure if I see the factors automatically or know 16x table.

[@adgf1x]

?=(45-12)/80=33/80.ans

[@anthony1947]

Did it in 10 seconds. Convert to 45 over 80 and 12 over 80 then subtract leaving 12 over 80

[@MrSummitville]

Say what???

[@anthony1947]

@MrSummitville I meant 33 over 80.... Slip of the finger !🤘

[@B.F.G.CAnimations]

Infinduss Howard

[@sheiladale6802]

Sometimes you bring in so much extraneous… talking so much. Why not show us how to do it THEN teach WHY this works. ???

[@AtangchoAtang-aka]

Please,your explanation is too long. Lcm of 9/16 and 3/20 is simply 320

[@B.F.G.CAnimations]

Ha ha ha

[@truckfump-no45]

That was nothing more than a word vomit.

[@thomasoneill3972]

Is anybody still awake in class?

[@dougresenbeck3164]

33/80

[@AC34D]

33/80

[@1995dodgetruck]

33/80

[@jimwalshonline9346]

33/80

[@generalmanagerformays587]

33/80