Answer:
387 miles / hour
Step-by-step explanation:
X be the maximum speed of plane and Y be the speed of wind.
Speed is the ratio of distance traveled to the time taken by the body.
When the plane travels against the wind, the speed of the plane is X - Y and when the plane is moving with the wind the speed is X + Y.
According to the formula
speed = \frac{distance}{time}speed=timedistance
X - Y = \frac{1720}{5}X−Y=51720
X - Y = 344 ....(1)
And
X + Y = \frac{1720}{4}X+Y=41720
X - Y = 430 ......(2)
Adding both the equations,
2X = 774
X = 387 miles/hour