Answer:
2.5 inches
Step-by-step explanation:
For the same-height prisms to have equal volumes, their base areas must be the same. If x is the unknown dimension of the rectangle, this requires ...
(5 in)^2 = (10 in)x
x = (25 in^2)/(10 in) = 2.5 in
The width of the rectangle is 2.5 inches.