Answer:
Step-by-step explanation:
R is the speed of the plane
S is the speed of the wind
(R-S)*7 = 7490 <--- against the wind
(R+s)*9 = 11610 <--- with the wind
Distributes:
7R - 7S = 7490
9R + 9S = 11610
Multiplies the top equation by 9
and the bottom equation by 7
63R - 63S = 67410
63R + 63s = 81270
126R = 148680
R=1180
Plugs into original first equation
(R-S)*7 = 7490
(1180-s)*7 = 7490
1180 - s = 7490/7
1180 - s = 1070
-s = -110
s = 110
The speed of the plane in still air is 1180
The spped of the wind is 110
This is awfully fast.
