3. Mortgage payment formula: (fixed rate!) . Write the basic equation: amount owed (T(k)) = owed last month (T(k-1)) plus interest (r) - payment P . try to back substitute to get values of T as functions of 7(0) and r only. Set T' at the end to be zero! and get a closed form solution. Use 360 months, and for rate of 5% for example, r = 5/(100 # 12). You might find these identities useful: Itata'ta't.= 1 - a if acl I tatatatoo.=- 1 - a*+1 1 -a