We start by splitting the shape into two rectangles as shown in the diagram below:
Area of shape A = 10' × 3' = 30'
Area of shape B = 6' × 2' = 12'
Total area = 30' + 12' = 42'
Area of shape A = 10' × 3' = 30'
Area of shape B = 6' × 2' = 12'
Total area = 30' + 12' = 42'