Following scenario: I open a savings account and I deposit 1,000 USD. Now, every year I deposit another 100 USD. The interest rate is 5%. I want to know how much money will be on that savings account in 20 years.
I understand that if the initial deposit had been 100 as well you could just do:
100 * 1/0.05 * (((1+0.05)^20)-1) or
C * 1/r * (((1+3)^N)-1)
But how do I bring the initial deposit into the equation?