Question 1010198
Rate times time equals distance, or rt=d and t = d/r.
Call the rate of the plane in still air, r.  Then we write
{{{90/(r-25) = 110/(r+25)}}}
Now cross-multiply and solve giving us
90(r+25) = 110(r-25)
90r + 2250 = 110r - 2750
-20r = - 5000
r = 250 mph