Sidney took out a payday loan of $1200 that charged an $85 fee. if the loan matures in 2 weeks, what is the appropriate effective interest rate of the loan?

The amount owed increases by $85 in two weeks. 

If the loan were "rolled over" at that point at the same interest rate, and this were done for a full year, the total amount owed would be 
(1285/1200)^26 * $1200 

If we subtract the original principle, $1200, and calculate the rest (the compounding interest) as a percentage of that principle, we get 

[(1285/1200)^26 * $1200 - $1200] / $1200 = 493%

That is right sorry i was gonna answer but i already saw his