Ihave a $500 in my account after 4 years of investing at 2.5% per year, how much money did i start with?

In stepmber, daniel and justin opened a business. during their first three months of business, their average monthly profit was $51. if during their first month, they lost $29, and during their second month, they gained $115, what was their profit or loss for their third plzzz i will give you 299 points