You can
put this solution on YOUR website! .
Cynthia + Sylvia = 13
(Cynthia + 5) + Sylvia = 13
2*Sylvia + 5 = 13
2*Sylvia = 13 - 5
2*Sylvia = 8
Sylvia = 8/2 = 4.
Then Cynthia = 4 + 5 = 9.
Answer. Cynthia is 9 years young. Sylvia is 4 years young.
Notice that I formatted my post in a way everything would be clear to you without words.