10% is 10 per cent, i.e 10 in every 100, or 1 in 10 which is 1/10.
So take 1/10 od $185.
This gives you $18.5 or $18.50
Since the fee is $18.50, then add that on to the money borrowed, $185, to get the amount of money to be paid back.
Return is : $185 + $18.50 = $203.50