Let A and B represent the volumes of prism A and B.
We were told that the 2 rectangular prisms have the combined volume of 432 ft³. This means that
A + B = 432
prism A has half the volume of prism B. This means that
A = B/2
Substituting A = B/2 into A + B = 432, we have
B/2 + B = 432
Multiplying each term in the equation by 2, it becomes
B + 2B = 864
3B = 864
B = 864/3
B = 288
A = B/2 = 288/2
A = 144
The volume of prism A is 144 ft^3 nad the volume of prism B is 288 ft^3