Example 5

Ernesto built a wooden car for a soap box derby. He is painting the top of the car blue and the sides black. He already has enough black paint, but needs to buy blue paint. He needs to know the approximate area of the top of the car to determine the size of the container of blue paint he should buy. He measured the length to be feet inches, and the width to be inch less than feet. What is the surface area of the top of the car? What is the most accurate area Ernesto can use to buy his paint?