How do you sole the problem below?
Kevin flies a plane against a headwind for 5600 miles. The return trip with the wind took 10 hours less time. If the wind speed is 5 mph, how fast does Kevin fly the plane when there is no wind?
Vdownwind = v + 5
Vupwind = v - 5
5600 = (v+5) t
5600 = (v-5)(t+10)
so
5600 = v t + 5 t
5650 = v t + 10 v -5 t
================
-50 = 0 +10 t -10 v
or t = v-5
go back up
5600 =(v+5)(v-5) = v^2 - 25
v^2 = 5625
v = 75