Answer:
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Let it be x years after that Jack's mother will be 3 times as old as Jack.
Set up equation and solve for x:
- 45 + x = 3(5 + x)
- 45 + x = 15 + 3x
- 3x - x = 45 - 15
- 2x = 30
- x = 15
After 15 years Jack will be 20 and his mother will be 60 years old.
