(1) [a] Suppose a payment of R dollars per month pays off a mortgage loan of 217.39R dollars in 25 years. You plan on buying a house. Assume that you must have a down payment of 10% of the house price and there is a transaction cost of 8% of the house price. both of which you can cover. Express the (maximum) house price you can afford as a function of the monthly mortgage payment, and the (minimum) monthly mortgage payment required as a function of the house price. (b) If the house price doubles, how do the (minimum) monthly mortgage payment required. down payment, and transaction costs change