A Certain Aircraft Can Fly 960 Miles With The Wind In 4 Hours And Travel The Same Distance Against The Wind In 6 Hours. What Is The Speed Of The Wind?

Make n (normal) the speed of the plane without wind resistance
make w the wind speed

With the wind
distance = 960 miles ; time = 4 hrs ; speed = 960/4= 240 mph

Against the wind
distance = 960 miles ; time = 6 hrs ; speed = 960/6 = 160 mph

Use these equations:
N - w = 160 mph (miles per hour)
n + w = 240 mph
n - w + n + w = 160 +240 mph
2n = 400 mph
n = 200 mph (speed of the plane in calm air)
200 + w = 240
w = 40 mph (wind speed)