math problem help

Question

You want to put a 4 inch thick layer of topsoil for a new 18 ft by 16 ft garden. The dirt store sells by the cubic yards. How many cubic yards will you need to order? The store only sells in increments of 1/4 cubic yards.

Answer 1

18 by 16 by 1/3 = 96 cubic feet= 96/27

= 32/9 cubic yards = 3 5/9 yd^3

a cubic foot = 1/27th of a cubic yard

32/9 divided by 1/4 = (32/9)(4) = 128/9 = 14 2/9 incremental sales needed

so you need 15