Use Excel's PMT and built$-$in mortgage functions to complete the dynamic mortgage refinancing model. Enter the necessary functions, formulas in cells C$9,$ C$10,$ F$4,$ F$9,$ F$10,$ C$15($must contain if$),$ and C$16.$ Complete the FindIndifRate$()$ Sub in VBA which solves for the rate of new mortgage for which the user will be indifferent between refinancing and keeping the original mortgage $($this rate will be displayed in C$19).$ You model should provide the answer to Solution? example as well as replicate the results for all $3$ examples.