Another word problem

[Guest]

I do not understand how this should be solved. Please help.
A six passenger plane cruises at 180 mph in calm air. If the plane flies 7 miles with the wind in the same amount of time as it flies 5 miles against the wind then what is the wind speed?

 

[Gene]

You may have heard that distance = speed times time.
7 = (180+x)*t
5 = (180-x)*t
Eliminate the "t" and solve for x.