Let s be the total amount you have deposit and m the number of months. Then we can model the amount as:
where k is the deposit each month and b is the initial deposit; in this case we have that k=60 and b=600, therefore the equations that models the amount you have is:
Now, the equation you have to solve to figure how many months you need to get 10000 is:
Solving for m we have that:
Therefore, it will take 166 months to save $10000.