Time and Distance | MathCelebrity Forum

Time and Distance

charlie leaves home going 40 miles per hour. When charlie is 9 miles from home, Danny starts after charlie from the same place, going 55 miles per hour. How long does it take Danny to catch up charlie?
 
Let h be the number of hours that pass when Charlie starts. We have the following equations:
  • Charlie: D = 40h + 9
  • Danny: D = 55h
Set them equal to each other:
40h + 9 = 55h

Subtract 40h from both sides:
15h = 9
h = 3/5

3/5 of an hour = 3(60)/5 = 36 minutes
 
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