Question 1017269: Two planes, which are 1680 miles apart, fly toward each other. Their speeds differ by 40 mph. If they pass each other in 2 hours, what is the speed of each?
Answer by ikleyn(52884)   (Show Source):
You can put this solution on YOUR website! .
Two planes, which are 1680 miles apart, fly toward each other. Their speeds differ by 40 mph.
If they pass each other in 2 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 +40 mph.
The distance between two planes decreases at the rate x + (x+40) = 2x + 40 mph.
You have this equation
 = 2.
Solve it. For it, multiply both sides by (2x + 40). You will get
1680 = 2*(2x + 40), or
1680 = 4x + 80, or
4x = 1600.
Hence, x =  = 400 mph. It is the speed of the slower airplane.
The speed of the faster is 400 + 40 = 440 mph.
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