You'll have to find the volume of the smaller rectangle and the larger rectangle separately, then add them together.
For the larger rectangle: V = length x width x height
V = 10 x 6 x 4 = 240
Now you use the same equation to find the smaller rectangle.
V = lwh
V = 4 x 3 x 6 = 72
Add the two volumes together to get the volume of the entire composite figure.
240 + 72 = 312
