Mathematics for IGCSE & O level - Mensuration (Section 10 - No. 30)
To find the area of a composite shape made of a rectangle and a triangle, you would:
Subtract the area of the triangle from the rectangle.
Multiply the areas of both shapes.
Add the areas of both shapes together.
Divide the areas of both shapes.
Explication
To find the area of a composite shape, find all the separate areas and add them.