Chris will be paid of $13,320,every year he puts $6000 each year, so in that case you could use your cacucator to by simply add $6000 twice. they also have to pay a five percentage oh the new cost which it would be $12000. then all you have to do is type in the final cost & considering they are paying both years of intrest which would be 10%, which would get you the total of everything is going to be $12600. In this case they only want one year of intrest, which is 300.
Hope this helped :)
