Suppose you deposit ​$600 in a bank account with a simple interest rate of 2.5​%. You want to keep your deposit in the bank long enough to earn at least ​$120 in interest. How long should you keep your deposit in the​ bank?
To earn at least ​$120 ​interes you should keep your deposit in the bank for blank year(s).

​(Round up to the nearest​ year please)