Question 219634
M=3x
J=x
In 7 years:
(3x+7)=2(x+7)
3x=7=2x+14
3x-2x=14-7
x=7 Jenny's age now.
3*7=21 Matthew's age now.
Proof:
3*7+7=2(7+7)
21+7=2*14
28=28