12) In a mine, 200 and 250 persons are deployed in the panel A and B (shown in the figure) respectively in the large shift. The panel produces 400 and 500 tons/day respectively .the resistance of panels A and B are 0.3 Ns2/m8 and 0.4Ns2/m8 respectively and the combined resistance of shaft and trunk airway is 0.5 Ns2/m8 .the operating static pressure of the fan in pa to provide the minimum air quantity in panel is? please do me afavor