Answer:
C. 39 ft²
Explanation:
Area of the outer rectangle which includes the white triangle
= length x width
= 5 x 9
= 45 ft²
Area of the white triangle
= 1/2 x base x height
= 1/2 x 4 x 3
= 6 ft²
Area of shaded region
= Area of rectangle - Area of triangle
= 45 - 6
= 39 ft²