Hello and HELP!!! U Mathematical GURUS!...

[SittingBull]

My niece needs to know how to solve this problem for a test.
Your help would be deeply appreciated!

Problem
u have saved $7000.00 toward the purchase of a new car costing 9000.00.
How long will the 7000.00 have to be invested at 9% compounded monthly to grow to 9000.00?

Forumlas,explanation of variables,etc... ,please.
Thanks
HappyPokering, [img]/images/graemlins/smile.gif[/img]
SittingBull