A rectangle has length c and width 2d. Another rectangle has length 4 and width (5-c). Write a simplified expression of their combined area.

The combined area is area of the first rectangle plus area of the second rectangle.

Area of first rectangle = c x 2d = 2cd

Area of second rectangle = 4 (5 - c) = 20 - 4c

Combined area = 2cd + 20 - 4c