Mikey, let's let P = principal amount, r = the monthly interest rate, n = the number of months, and M = the monthly payments.
Then, we have that M = P(1+r)n r / [(1+r)n-1]. Remember that r = .062/12, because we want the monthly rate.
So, we have that M = [120000(1 + .062/12)180(.062/12)] / [(1 + .062/12)180 - 1].
Plug all that into your calculator for your answer.