The area of a grassy plot is 480 sq. m. If each side had been 5 m longer, the area would have been increased by 245 sq. m. Find the length of the fence to surround it.

Let the length and breadth of the plot be l and b metres respectively
Then, lb = 480
And,
$$\eqalign{ & \left( {l + 5} \right)\left( {b + 5} \right) = 725 \cr & \Rightarrow lb + 5\left( {l + b} \right) + 25 = 725 \cr & \Rightarrow 5\left( {l + b} \right) + 505 = 725 \cr & \Rightarrow \left( {l + b} \right) = \frac{{220}}{5} \cr & \Rightarrow \left( {l + b} \right) = 44\,\,\,\,\left[ {\because lb = 480} \right] \cr} $$
∴ Length of the fence :
$$\eqalign{ & = 2\left( {l + b} \right) \cr & = \left( {2 \times 44} \right)m \cr & = 88\,m \cr} $$