At maximum speed , an airplane travels 1680 miles against the wind in 5 hours flying with the wind , the plane can travel the same distance in 4 hours. let x be the maximum speed of the plane and y be the speed pf the wind. what is the speed of the plane with no wind

The speed of plane is 378 mph in still air.

Step-by-step explanation:

Let x be the maximum speed of the plane.

Let y be the speed of the wind.

Distance an airplane travels = 1680 miles against the wind in 5 hours

So, equation  becomes,

or      .....(1)

And with the wind, equation becomes,

or    .... (2)

Solving both equations, we get;

x = 378

And x+y=420

Hence, the speed of plane is 378 mph and the speed of wind is 42 mph.

maybe - definition of supplementary angles. im not sure. sorry

step-by-step explanation: