It seems the real problem here is 1) determining the amount of time 2) determining the interest rate Using a loan payment calculator, http://www.1728.org/mortmnts.htm we determine that $235,000.00 financed for 30 years at a 7.7215% interest rate yields a monthly payment of $1,678.94
When financing a mortgage, (for example 30 years) in the early years of the mortgage, the vast majority of the payment goes to interest. So, for your first payment, of $1,678.94, the amount going to interest is $1,512.13 and the amount going to principal is $166.81.
Basically, after spending $1,678.94 on your first mortgage payment, you actually own (the equity) $166.81.