Monica has decided that she wants to build enough retirement wealth that, if invested at 9 percent per year, will provide her with $4,800 of monthly income for 20 years. To date, she has saved nothing, but she still has 25 years until she retires.

How much money does she need to contribute per month to reach her goal? (Do not round intermediate calculations and round your final answer to 2 decimal places.)

I got 475.86 as an answer but I'm unsure of the steps on how to do it. Please show the steps or formulas used.