Question 814866
I assume it is asking for the rate of the jet plane and the prop plane.
Let us call the speed of the prop plane x and so as the jet plane is travelling three times as fast its speed with b3 3 times x, otherwise written as 3x

So speed of prop plane = x
Speed of jet plane = 3x

The time it takes for the plane to travel its distance = distance divided by speed.
So:
Time for the jet plane journey = 1700/3x hours
Time for the prop plane journey = 300/x hours

The total time for the journey is 5 hours, so you add the time for each leg of the journey which will equal 5 hours.

This is written as 1700/3x + 300/x = 5

Now solve for x:

Multiply each by 3:
5100/3x + 900/x = 15
Simplify:
1700/x 900/x = 15

Multiply each by x:
1700x/x + 900x/x = 15x

1700 + 900 = 15x (as the x's in each fraction cancel each other out)

2600 = 15x

divide each side by 15 to find x:

2600/15 = 15x/15

173 1/3 = x

so the speed of the the prop plane is 173 1/3 miles per hour
and multiply this by 3 (as the speed of the jet plane is 3 times the speed of the prop plane) to find the speed of the jet plane = 520 miles per hour