Tim and Mary consistently added money into each of their bank accounts every month for the same number of months. The amount of money in Tim's bank account is modeled by the function f(x), with x representing the number of months f(x) = 250x + 6000 Mary deposited $500 into her bank account each month. If Tim and Mary had the same amount of money in their accounts after 10 months, how much money was in Mary's account before her 10 months of regular savings? Justify your answer.