The old volume was:
2 x 6 x 10 = 120 cubic inches
The new volume is:
3 x 5 x H = 120 cubic inches
15H = 120
H = 120/15
H = 8 inches
2 x 6 x 10 = 120 cubic inches
The new volume is:
3 x 5 x H = 120 cubic inches
15H = 120
H = 120/15
H = 8 inches