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In five years time, John will be three times as old he was nine years a go. How old is he now?
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Let x be John's age now.
In five years time, John's age will be (x+5).
Nine years ago John was (x-9) years.
The condition says that
x + 5 = 3*(x-9).
Simplify and solve it for x:
x + 5 = 3x - 27 ---> 5+27 = 2x ---> 2x = 32 ---> x = = 16.
Answer. John is 16 years old now.
Check: 1) 16+5 = 21; 2) 16-9 = 7; 3) 21 = 7*3. Checked - OK!
For solved age problems see the lessons
- Age problems and their solutions
- A fresh formulation of a traditional age problem
- Really intricate age word problem
- Selected age word problems from the archive
in this site.