The length and breadth of a rectangle are in the ratio 9 : 5.If its area is 720 Sq.m, find its perimeter.

Suppose that the length and breadth of the rectangle are $l,b$ resepctively

The length and breadth of the rectange are in the ratio $9:5$

Given $\frac{l}{b}=\frac{9}{5}$

Given that hte area of the rectangle is $720$ sqaure meters

hence, $lb=720$

$\begin{array}{rcl}\frac{9}{5}{b}^2& =& 720\\ b^2& =& 400\\ b& =& 20\end{array}$

hence, the length is 

$\begin{array}{rcl}l& =& \frac{9}{5}b\\ & =& 36\end{array}$

Therefore, the perimeter of the rectangle is $2\left(l+b\right)=2\left(56\right)=\boxed{112 meters}$