Question 1018976: Five years ago, David is 4 times as old as Anna. The present sum of their ages is 25. What are these ages? Found 2 solutions by ikleyn, MathTherapy:Answer by ikleyn(52781) (Show Source):
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Five years ago, David was 4 times as old as Anna. The present sum of their ages is 25. What are their ages?
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Let D = David's present age, A = Anna's present age.
Five years ago David's age was D-5, while Anna's age was A-5,
and the condition says that
D-5 = 4*(A-5).
This is your first equation.
The second is
D + A = 25.
Now express D = 25 - A from the second equation and substitute it into the first. You will get
(25-A) - 5 = 4*(A-5).
Simplify and solve it:
30 - A = 4A - 20,
20 + 20 = 4A + A,
5A = 40,
A = = 8.
Thus Anna is 8 years now.
Hence, David is D = 25 - A = 25 - 8 = 17 years now.
