Jesse worked at the pool all summer and saved $500. Her parents want her to put the money into a bank account, where she would earn 2% simple interest monthly on her principal deposit of $500. How much will she make in interest?

You need to know how long it was in her account then you would multiply the .2 by the 500$ and get the total for the first month. Then .2 by the total of the first month not $500 to get the second month. You continue this for as many months as it asks you and keep multiplying your new amount. The final step is to subtract the final month balance by $500 to get the amount she makes in interest.