Question

A rectangular section of granite is being cut so that the length is 3 times the width. The perimeter of the section must be less than 320 inches.

Answer 1

Answer:

Let x inches be the widht of the section. If the length is 3 times the width, then the length is 3x inches.

The perimeter of the rectangle is

P=2(\text{width + length})P=2(width + length)

Hence,

P=2(x+3x)=2\cdot 4x=8xP=2(x+3x)=2⋅4x=8x

The perimeter of the section must be less than 320 inches, so

\begin{lgathered}8x<320\\ \\x<40\\ \\3x<120\end{lgathered}

8x<320

x<40

3x<120