Answer:
140 ft³
Explanation:
imagine the prism is standing on one of its triangular sides.
then it becomes a regular object with the volume
base area × height
the base area is the area of the triangle
baseline × inner height / 2
in our case
4 × 7 / 2 = 14 ft²
so for the volume we have
14 × 10 = 140 ft³