Let x and y be the number of months and the total balance of the account, respectively. Therefore, when x=0, y=$500 (starting amount) and, after 1 month, $75 are added to that amount, after 2 months, 2*$75, and so on.
Thus, the equation is
Where 75 is the slope of the line (m=75), and the y-intercept is equal to 500 (b=500).
2 years is equal to 2*12=24 months; therefore,
After two years, the total balance is $2300.