7. Evaluate the height of the cuboidal box

The perimeter of the top of the cuboidal box is 400 \(cm\). If the cost of painting the box at the rate of \(₹\)18 per \(cm^2\) is \(₹\)36000, find the height of the box.

 

[Hint: Area of four walls \(=\) Lateral surface area]