You need to find the difference in the volumes.
Glass box (inner box): V = LWH = 9 in * 7 in * 12 in = 756 in^3
Larger box: V = LWH = 10 in * 10 in * 15 in = 1500 in^3
Now we subtract the smaller volume from the larger volume.
1500 in^3 = 756 in^3 = 744 in^3
Answer: 744 in^3
