SOLUTION: Two planes, which are 2320 miles apart, fly toward each other. Their speeds differ by 80 mph. If they pass each other in 4 hours, what is the speed of each?

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Question 1017257: Two planes, which are 2320 miles apart, fly toward each other. Their speeds differ by 80 mph. If they pass each other in 4 hours, what is the speed of each?
Answer by ikleyn(52879) About Me  (Show Source):
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Two planes, which are 2320 miles apart, fly toward each other. Their speeds differ by 80 mph.
If they pass each other in 4 hours, what is the speed of each?
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Let x be the speed of the slower plane, in mph.
The the speed of the other plane is x +80 mph.

The distance between two planes decreases at the rate x + (x+80) = 2x + 80 mph.

You have this equation

2320%2F%282x%2B80%29 = 4.

Solve it. For it, multiply both sides by (2x + 80). You will get

2320 = 4*(2x + 80),   or

2320 = 8x + 320,   or

8x = 2000.

Hence, x = 2000%2F8 = 250 mph. It is the speed of the slower airplane.
The speed of the faster is 250 + 80 = 330 mph.