An aircraft travels with the wind for 120 miles in 0 point 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
0 point 75 times x plus y is equal to 1 2 0 x minus y is equal to 1 2 0
B
0 point 75 times x plus y is equal to 120 x plus y is equal to 120
C
120 times x plus y is equal to 0 point 75 120 times x minus y is equal to 1
D
120 times x minus y is equal to 0 point 75 120 times x plus y is equal to 1
Explanation
Flying with the wind, the plane’s speed relative to the ground is x + y. Using distance = rate × time gives 120 = 0.75(x + y). Against the wind, its speed is x − y, and the one-hour return trip gives 120 = 1(x − y), or x − y = 120. These are the equations represented by choice A.
AI-written and checked against the verified answer.