In positively skewed distributions, the mean is usually greater than the median, which is always greater than the mode
The monthly payment would be $289.33
$104,000 - $24,000 = $80,000
$80,000 x %8.5 interest = $6,800
$80,000 + $6,800 = $86,800 (total being paid back)
12 (total of months in a year) x 25 (number of years) = 300
Divide $86,800 by 300 and your monthly payment is $289.33

all we can really cancel is one of the (x-5) and the "x", is all.
The markup cost is 475 dollars!
Hope this helps!
♤MidnightQueen