The average area of a rectangle and a triangle is 40 . The triangle has a base of 8 m and a height of 9 m. If the rectangle has a width of 4 m, what is its perimeter?
The total area of the two shapes is 40 × 2 = 80 .
The length of the rectangle is area ÷ width = 44 ÷ 4 = 11 m.
Therefore, the perimeter of the rectangle is 11 × 2 + 4 × 2 = 30 m.