Question

Two planes left the same airport traveling in opposite directions. The first plane left at 9:00 a.M. And 2.25 hours later, the two planes were 1825 miles apart. The second plane left at 10:00 a.M. And its average rate was 108 miles per hour slower than the first plane's average rate. Let x represent the first plane's average rate. What was the first plane's average rate?

Answer 1

Answer: x = 560 miles/hr

Explanation:

Let speed of first plane = x

Let speed of second plane = y

x-y =108 (first plane is faster)

It took first plane 2.25 hrs to be 1825 miles apart.

Distance moved after 2.25 hrs =2.25x

It took second plane 1.25 hrs to be 1825 miles apart

Distance moved after 1.25 hrs =1.25y

So 2.25x + 1.25y = 1825 --------1

Put x = 108+y in eqn 1

2.25(108+y) + 1.25y= 1825

243 + 3.5y = 1825

3.5y= 1582

y = 452

x = 108 + 452 = 560 miles/hr