a plane flying with the wind went 600 miles in 3 hours The r

a plane flying with the wind went 600 miles in 3 hours. The return trip,flying against the wind took 4 hours. Find the rate of the plane in calm air and the rate of the wind.

Let the speed of the plane be x
Let the speed of the wind be y
3(x+y)=600 --->3x+3y=600
Solve for y in the first equation:
3y=600-3x
y=200-x (subsitution)

4(x-y)=600
4x-4y=600
Subsitute for y:
4x-4(200-x)=600
4x-800+4x=600
8x=1400
x=175

y=200-175
y=25.