Slit the shape into a rectangle and two triangles:
Rectangle = 9 x 8 = 72 sq. Ft.
Triangle = 1/2 x 8 x 2.5 = 10 sq. Ft x 2 = 20 sq. Ft.
Total area = 72 + 20 = 92 sq. Ft.
3 coats x 92 = 276 sq ft worth of paint.
1 quart covers 200 so he would need to buy 2 quarts:
2 x $8.97 = $17.94 total