An aircraft travels with the wind for 120 miles in 0. 75 of an hour. The return trip is flown against the wind and takes exactly 1 hour. Which system of linear equations represents x, the speed of the plane in miles per hour, and y, the speed of the wind in miles per hour? recall the formula d = rt. 0. 75(x + y) = 120 x − y = 120 0. 75(x − y)= 120 x + y = 120 120(x + y) = 0. 75 120(x − y) = 1 120(x − y) = 0. 75 120(x + y) = 1.