Answer:
60 cm^3
Explanation:
You're thinking it's 4 * 3 * 120, but you forgot that the triangle base is not 4 * 3 but rather half of that, because a triangle is half of a rectangle. So the area of the triangle base is 6.
Multiplying by the length of the rectangular base (10) gives 6 * 10 = 60 cm^3.
I hope this helped!