Respuesta :

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.