My Ex Husband Wants To Settle Back Child Support

My ex- husband Bruce Wells born 4-19-55 and lives in Jerseyville Il. contacted me on back child support that he owes me for our 33 old son. He owes for Jimmy Leroy Wells born 4-23-77 who lives in Bloomington Il. My name is Deborah Weed, formerly Deborah- Baker- Wells. We were married in Grafton Il. on October 26th 1974. We divorced in January 1987. He never payed support to me. I would like to know how much actual child support he owes me. If you can help me with this or point me in the right direction, I would appreciate it very much. Thank you for your time.
Deborah Weed