Can someone please help me figure this out, I've been stuck on it forever!

Part A: Your client is exactly 45 years old and currently has $500,000 in savings. What constant amount per year must they save to withdraw $120,000 every year starting at age 63 until the end of age 85 . The client would like to have $15,000 left over at the end of their 85 th year to leave to charity. Assume that the account earns 3.75% per year