N=20*12; R=0.06/12;PV=25000; PMT=PV*R*((1 + R)^N) / ((1 + R)^(N) - 1);print"LOAN PMT =$",PMT
a - LOAN PMT =$ 179.11
b - $179.11 x 20 years x 12 =$42,986.40 - Total principal + interest
c - $42,986.40 - $25,000 =$17,986.40 Total interest paid
17,986.40 / 42,986.40 =41.84% paid toward interest
25,000 / 42,986.40 =58.16% paid toward principal.
Note: I got to go now. It is my bed time !!.