Let x be the speed of the wind, in miles per hour.
Then the speed of the airplane with the wind is (220+x) miles per hour;
against the wind (220-x) miles per hour.
The time equation is
= .
To solve it, cross-multiply
540*(220-x) = 340*(220+x).
Simplify and solve
540*220 - 540x = 340*220 + 340x
540*220 - 340*220 = 340x + 540x
x = = 50.
ANSWER. The wind speed is 50 miles per hour.