Question

A rectangular prism is 18 inches tall and has a square base whose length is 9 inches. Oliver plans to cover the top and bottom of the rectangular prism with material A, which costs 2 cents per square inch. He then plans to cover the other four faces of the prism with material B, which costs 1.5 cents per square inch. How much money will Oliver spend on the materials to cover the rectangular prism?

Answer 1

base area = 9^2 = 81
each face has area 9*18 = 162

now just multiply each area by its cost and add up the proper number of faces.