It can be concluded that:1500x =1200y =1500x-1200y = 0 (1).

x+Y = 9(2)= 1200 x+ 1200Y = 10800(3)

Add (3)+( 1) to get:1500x+1200x =10800.

X=4

Substituting X=4 into (2) gives Y=5.

So X=4.

Y=5 4* 1500=6000 km.

Answer: Go with the wind for 4 hours, come back with the wind for 5 hours, and fly back 6000 kilometers with the wind.