Chapter 9.3, Problem 10OE

To determine

To find: The dimensions of the rectangle.

Answer to Problem 10OE

The length of the rectangle is $25\text{cm}$ and the breadth is $10\text{cm}$ .

Explanation of Solution

Given:

The length of the rectangle is $5\text{cm}$ less than three times of the width.

The perimeter of the rectangle is $70\text{cm}$ .

Calculation:

Consider the width of the rectangle is $b$ .

Consider length of the rectangle is $5\text{cm}$ less than three times of the width that is,

  $l=3b-5\text{cm}$

Consider the perimeter of the rectangle is,

  $2\left(l+b\right)=P$

Then,

  $\begin{array}{l}2\left(3b-5\text{cm}+b\right)=70\text{cm}\\ 6b-10\text{cm}+2b=70\text{cm}\\ \text{8}b=80\text{cm}\\ b=10\text{cm}\end{array}$

Then, the length of the rectangle is,

  $\begin{array}{c}l=3\left(10\text{cm}\right)-5\text{cm}\\ =25\text{cm}\end{array}$