I need to find the number of years that it would take for any amount of money to triple if it were deposited at a 4% annual interest rate that is...

I need to find the number of years that it would take for any amount of money to triple if it were deposited at a 4% annual interest rate that is compounded annually and explain my reasoning. I have tried numerous times though I have not found what step I am missing. I would appreciate any assistance.