Question 1177337

let the rate of the plane in still air be x

and the rate of the wind be y

rate with wind =( x+y) mph

distance = 920 miles

time = 2 hours

d/r = t
920/(x+y) =2

2x+2y =920
/2
x+y = 460 --------------(1)

Against wind rate = (x-y)

920/(x-y) = 4

4x-4y = 920
/4
x-y = 230------------------(2)

Add equation (1) & (2)

2x = 690
x= 345 
the rate of the plane in still air 345 mph


the rate of the wind be 115 mph