Step-by-step explanation:
for such regular figures the volume is always
ground area × height.
the volume of the green box (bar on a rectangle) at the bottom is therefore
16×7×3 = 336 in³
the volume of the red object on top (based on a right-angled triangle) we get
5×3/2 × 6 = 5×3×3 = 45 in³
so, the total volume is the sum of both sub-volumes :
336 + 45 = 381 in³
