surface area/wall area=2(height times width)+2(height times depth)+2(width times depth)
lets say 3=height depth=19 width=12
2(3 times 12)+2(3 times 19)+2(12 times19)=2(36)+2(57)+2(228)=72+114+456=642
2 coats of paint so surface area times 2 642 times 2=1284 assuming 30m means 30 <u>square</u> meters we divide 1284 by 30 and get 1284/30=42 and 4/5 or 42.8 then find how many cans by dividing by 4 42.8/4=10 and 1.4/2=10.7, but you cant buy 0.7 of a can so round up and get 11 cans of paint
First, find the length L^2+W^2=D^2 )L for length, W for width, D for diagonal) L^2=25^2-15^2=625-225=400 L=20 A=1/2 of L*W= (1/2)*20*15=150 square inches