Since he is investing the same amount monthly, we have to apply annuity formula. And it is planned for the future. So that, we'll apply future value annuity formula. The formula is [tex]FV=A[ \frac{(1+ \frac{r}{s})^{Ns} -1 }{r} ][/tex], where A is the monthly payment, r is the percentage rate, s is 12 (monthly compound) and N is the time, which is 30. Plugging the numbers into the formula, we write that [tex]FV=155[ \frac{(1+ \frac{0.037}{12} )^{12*30} - 1 }{0.037} ][/tex] = $8485.450857