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| Question 846191:  Five years from now, a father's age will be three times his son's age, and five years ago, he was seven times as old as his son was.  How do I set up this problem to solve as a system?
 Answer by ankor@dixie-net.com(22740)
      (Show Source): 
You can put this solution on YOUR website! Let f = father's age let s = son's age
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 Write an equation for each statement, smplify.
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 "Five years from now, a father's age will be three times his son's age,"
 f + 5 = 3(s+5)
 f + 5 = 3s + 15
 f = 3s + 15 - 5
 f = 3s + 10
 "and five years ago, he was seven times as old as his son was."
 f - 5 = 7(s-5)
 f - 5 = 7s - 35
 f = 7s - 35 + 5
 f = 7s - 30
 Use this to replace f in the 1st equation
 7s - 30 = 3s + 10
 You should be able to solve this now. Check your solutions in both statements
 
 How do I set up this problem to solve as a system?
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