Question

On a 1 mile track, Runner A has made 18 laps in the time it took Runner B to make 8 laps. If Runner A is running 5 mph faster than Runner B, how fast is each of them running?

Answer 1

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Answer:

• A: 9 mph
• B: 4 mph

Step-by-step explanation:

Let b represent the speed of runner B. then the ratio of speeds is ...

  b/(b+5) = 8/18

  18b = 8(b +5) . . . . cross multiply

  10b = 40 . . . . . . . . subtract 8b

  b = 4 . . . . . . . . . . . divide by 10

Runner B's speed is 4 mph; runner A's speed is 5 mph more.

Runner A is running at 9 mph; Runner B is running at 4 mph.