Measures of Central Tendency: Mean

Keeping with the tradition of giving red envelopes during the Chinese New Year, you and your cousins always exchange envelopes in order to pass along good luck. In your group of people, the tradition is for every person to give a red envelope to every person who is younger than them, with an amount of money proportional to the age difference. The ages in this group are $1$, $30$, $32$, $35$, $36$, $37$, and $39$. One of the people ends up giving and receiving the exact same amount of money. What is the age of that person?