math
posted by KaRon on .
a mother wants to $9000 for her son's future education. She invested a portion of the money in a bank certificate(CD account) which earns 4% and the reminder in a savings bond that earns 7%. If the total interest earned after one year is $540, how much money was invested in the CD account

Assuming 9000 was invested, then if x was at 4%, then 9000x was at 7%.
.04x + .07(9000x) = 540
x = 3000
$3000 in CD
$6000 in savings