Let x = the speed of the plane, mph
Let y = the speed of the wind., mph
When flying with a tailwind, the effective speed of the plane is (x + y), therefore
x + y = 376 (1)
When flying back against the wind, the effective speed is (x-y), therefore
x - y = 312 (2)
Add (1) and (2).
2x = 376+312 = 688
x = 344 mph
y = 376 - x = 32
Answer:
Plane: 344 mph
Wind: 32 mph