Question 1049918
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. ☺☺☺☺