SOLUTION: In 3 years, david will be 3 times as old as his sister Marina, a year ago, David was 7 times as old as Marina. how old are they now?

Question 1103437: In 3 years, david will be 3 times as old as his sister Marina, a year ago, David was 7 times as old as Marina. how old are they now?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = David's age now
Let = Marina's age now
------------------------------
(1)
(2)
------------------------------
(1)
(1)
and
(2)
(2)
-------------------------
Add the equations
(1)
(2)
-------------------------

and
(1)
(1)
(1)
---------------------
David is 15 now
Marina is 3 now
--------------------
check:
In 3 yrs David is 18
In 3 yrs Marina is 6

OK
---------------------
1 yr ago David was 14
1 yr ago Marina was 2

OK

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