John needs to paint one wall in his school he knows that 1 can of paint covers an area of 24 square feet

Since I don't the dimensions of the wall I am just going to say its 15 ft high and 30 feet long, so that it would appear to be an average sized wall. so using that the surface area of the wall is 450 feet, and saying that each can of paint covers 25 so. feet he would need 18 cans of paint