I'm putting money into a bank account that earns a 9.0% APR with monthly compounding. I plan to invest $400 semi-annually, as well as a...

I'm putting money into a bank account that earns a 9.0% APR with monthly compounding. I plan to invest $400 semi-annually, as well as a to‐be‐determined initial amount today. How much must I invest today to have a total account balance of $30,000 in 7 years?