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Sally is 54 years old, and her mother is 80. How many years ago was Sally’s mother three times her age?

 Aug 25, 2019
 #1
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So you can give x=1/3. And so sally 54-x is what Sally’s age was.

41 years ago Sally was 13 and her mother was 39.

 Aug 25, 2019
 #2
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I will make it X years ago

 

\(80-X=3(54-X)\\ 80-X=162-3X\\ 80-X+3X=162-3X+3X\\ 80+2X=162\\ 2X=82\\ X=41 \)

 

So it was 41 years ago,  just like guest said :)

 Aug 25, 2019

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