SOLUTION: Mary's son was one fifth of her age 5 years ago. In 5 years time, if her son's age is multiplied by 3, it will be 8 more than her age. What is Mary's current age?

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Question 941684: Mary's son was one fifth of her age 5 years ago. In 5 years time, if her son's age is multiplied by 3, it will be 8 more than her age. What is Mary's current age?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The language is a little tricky here
Hope I'm interpreting it right
Let +m+ = Mary's age now
Let +s+ = her son's age now
-----------------
(1) +s+-5+=+%281%2F5%29%2A%28+m+-+5+%29+
(2) +3%2A%28+s+%2B+5+%29+=+%28+m+%2B+5+%29+%2B+8+
-------------------------------
(1) +5%2A%28+s+-+5+%29+=+m+-+5+
(1) +5s+-+25+=+m+-+5+
(1) +5s+-+m+=+20+
--------------------
(2) +3s+%2B+15+=+m+%2B+13+
(2) +-3s+%2B+m+=+2+
----------------------
Add the equations
(1) +5s+-+m+=+20+
(2) +-3s+%2B+m+=+2+
--------------------
+2s+=+22+
+s+=+11+
plug this back into (1) or (2)
(2) +-3s+%2B+m+=+2+
(2) +-3%2A11+%2B+m+=+2+
(2) +-33+%2B+m+=+2+
(2) +m+=+35+
Mary's current age is 35
check:
(1) +5s+-+m+=+20+
(1) +5%2A11+-+35+=+20+
(1) +55+-+35+=+20+
(1) +20+=+20+
OK