SOLUTION: The sum of the ages of two cosins is 15. In 3 years the older cousin will be twice as old as the younger cousin. How old is the cousin now?

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Question 1049918: The sum of the ages of two cosins is 15. In 3 years the older cousin will be twice as old as the younger cousin. How old is the cousin now?
Found 2 solutions by jorel555, advanced_Learner:
Answer by jorel555(1290) About Me  (Show Source):
You can put this solution on YOUR website!
Let m and n represent the two cousins. Then m+n=15. In three years n will be twice as old as m, so 2(m+3)=n+3. So:
2m+6=n+3
2m+3=n
m+2m+3=15
3m=12
m=4
n=11
The older cousin is now 11 years old. ☺☺☺☺

Answer by advanced_Learner(501) About Me  (Show Source):
You can put this solution on YOUR website!

x%2By=15
y%2B3=2%28x%2B3%29
Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
+system%28+%0D%0A++++1%5Cx+%2B+1%5Cy+=+15%2C%0D%0A++++2%5Cx+%2B+-1%5Cy+=+-3+%29%0D%0A++We'll use substitution. After moving 1*y to the right, we get:
1%2Ax+=+15+-+1%2Ay, or x+=+15%2F1+-+1%2Ay%2F1. Substitute that
into another equation:
2%2A%2815%2F1+-+1%2Ay%2F1%29+%2B+-1%5Cy+=+-3 and simplify: So, we know that y=11. Since x+=+15%2F1+-+1%2Ay%2F1, x=4.

Answer: system%28+x=4%2C+y=11+%29.