CPM Homework Banner

Home > CC3 > Chapter 7 > Lesson 7.2.5 > Problem 7-86

7-86.
  1. Mr. Crow, the head groundskeeper at High Tech Middle School, mows the lawn along the side of the gym. The lawn is rectangular, and the length is 5 feet more than twice the width. The perimeter of the lawn is 250 feet. Homework Help ✎

    1. Define a variable and write an equation for this problem.

    2. Solve the equation that you wrote in part (a) and find the dimensions of the lawn.

    3. Use the dimensions you calculated in part (a) to find the area of the lawn.

Recall that the equation of a perimeter is 2l + 2w. Use the information to make an equation for the perimeter with only one variable and set it equal to 250, which is the given perimeter.

Let w represent the width of the lawn:
2w + 2(2w + 5) = 250.

Start by distributing the two to the terms in parentheses and solve from there for w.
Once you find w, substitute it into an equation for l: 2(2w + 5) = length.

The area of a rectangle is length • width.