You want to tile your kitchen floor. The floor measures 18 ft by 9 ft. How many tiles, each a square with side 1 1 2 ft, should you purchase for the job?
Square footage to be covered = 18 * 9 = 162 ft^2 (A)
Area that each tile covers = 1.5 ft^2 (B)
So.....tiles needed = A /B = 162/ 1.5 = 108