Question

How many gallons of paint will you need to paint a bedroom that is 10 ft by 14 ft with walls that are 7 1/2 ft high? The walls will need two coats to cover the old paint.
How many gallons of paint are needed to paint the ceiling of the same room in the last question, one coat of paint will suffice.

Answer 1

you have two walls that are  10 by 7.5 so 75 feet ^2 in area each

you have another two walls that are 14 by 7.5  so 105 feet^ 2 each

so all of that together is 360 feet^2 to cover for one coating, so you have 720 feet^2 to cover for 2 coats on the walls. so take that and divide it by the area that one gallon would cover, then round up giving you how many gallons you would have to buy

for the ceiling you do the same, the area is 140 and you only need one coat