I am totaly stuck on this problem been at it for over an hour so my search for help has guided me to this forum

A young executive deposits $300 at the end of each month for 8 years and then increases the deposits. If the account earns 7.2%, compounded monthly, how much (to the nearest dollar) should each new deposit be in order to have a total of $400,000 after 25 years

stuck

I think i am suppose to calc the simple annuity for 8 years then minus from the total of 400,000 then calc the remander for 17 years anyone help?