The length and breadth of a rectangle are in the ratio 4:5. If its perimeter is 162 m, find its area.

Given, 

length : breadth = 4 : 5, 

Perimeter = 162 m

Let , length = 4x  

        breadth = 5 x

Perimeter = 2 (l + b)

162 = 2 (4x + 5x)

162 = 2 (9x)

162 = 18x

x = $\frac{162}{18}$ = 9

Hence, length = 4x = 4 x 9 = 36 m

             breadth = 5x = 5 x 9 = 45 m

Area = l x b

        = 36 x 45

       = 1620 m²