Answer: -
96 jet engines would be needed to make 24 model airplanes.
Explanation: -
We are told that
1 model airplane = 1 body + 2 wings + 4 jet engines + 1 tailpiece.
Thus,
24 model airplanes = 24 x (1 body + 2 wings + 4 jet engines + 1 tailpiece)
= 24 body + 48 wings + 96 jet engines + 24 tailpiece.
Thus we see that 96 jet engines would be needed to make 24 model airplanes.