The breadth of the rectangle is $\frac{3}{4}$th of its length and the perimeter of rectangle is 140 cm. Find the length and breadth of the rectangle.

Given: The breadth of the rectangle is $\frac{3}{4}$th of its length and the perimeter of rectangle is 140 cm

To do: Find the length and breadth of the rectangle.

Solution: 

Let the length of the rectangle be $y$

The breadth of the rectangle  would be $\frac{3y}{4}$

Perimeter of rectangle = $2(l + b) = 2(y + \frac{3y}{4}) = 2 \times \frac{7y}{4}$ = 140 cm

So, $y = 140 \times \frac{2}{7} = 40 cm$;  $\frac{3y}{4} = \frac{3}{4} \times 40$ = 30 cm

So length of rectangle = 40 cm and breadth of rectangle = 30 cm