If the area of the rectangle is 105 cm² . Its length is (4x 5) cm and breadth is (2x 5)

cm, find the perimeter?

Note: Please check your question once more because here we cant find the perimeter for the given dimensions.
Area of rectangle = length $\times$ breadth = $\left(4x-5\right)\times \left(2x-5\right)$ = 105
This forms a quadratic equation in which roots are not real. So we cant find the perimeter.