Stephen C. answered 07/09/19
SAT Math, Algebra, Trig, PreCalc Tutor
Let P be the Plane's rate (speed) in still air.
Let W by the rate of the Wind.
Then the total rate against the wind will be P - W.
And the total rate WITH the wind will be P+W.
We use our rate formula (Distance = Rate * Time) twice:
3605 = (P-W)*5
4605 = (P+W)*5
Adding the 2 equations together gives us
8210 = 10*P
or
P = 821 km/hr
and
5*W = 5*P - 3605
W = P - 721 = 821 - 721 = 100 km/hr