Word problem question about investments
I've been having trouble with this word problem and wondered if anyone could shed some light. If you could explain how it's done, that'd be great! Thanks!
A mother wants to invest $15,000.00 for her son's future education. She invents a portion of the money in a bank certificate of deposit (CD account) which earns 4% and the remainder in a savings bond that earns 7%. If the total interest earned after one year is $900.00, how much money was invested in the CD account?