b) Write a class named WallPaint that has a WallDimension object as a field. The WallPaint class should also have a field for the cost of the wall per square metre. The WallPaint class should have a method that returns the total painting cost of the wall.

The BinaPaint Company has asked you to write a program that calculates the price of painting for rectangular walls. To calculate the price, you multiply the area of the wall (length times width) by the price per square metre of wall. For example, the area of wall that is 15 metres long and 12 metres wide is 180 square metres. To paint that wall that costs RM20 per square metre would cost RM3,600.00 (15x12x20 = 3,600) You are required to apply three classes: WallDimension, WallPaint, and PaintCalculator. The PaintCalculator contains the main method that will apply WallDimension and Wallpaint classes. The following UML diagram shows possible class design and the relationships between the WallDimension class and WallPaint class. WallPaint size: WallDimension - paintCost: double +WallPaint (dim: WallDimension, cost: double) +get TotalCost(): double +toString(): String WallDimension - length: double width: double +WallPaint (dim: WallDimension, cost: double) +get TotalCost(): double +toString(): String FIGURE Q2