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 is equal to r t
Answer
A
120 times x minus y is equal to 0 point 75 120 times x plus y is equal to 1
B
0 point 75 times x plus y is equal to 1 2 0 x minus y is equal to 1 2 0
C
0 point 75 times x plus y is equal to 120 x plus y is equal to 120
D
120 times x plus y is equal to 0 point 75 120 times x minus y is equal to 1
Explanation
With the wind, the plane’s speed is x + y, so the distance equation is 0.75(x + y) = 120. Against the wind, its speed is x − y, and the one-hour trip gives 1(x − y) = 120. These equations match choice B.
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