431.2 is the answer to your question
$13, 666.67
because you would do 820 divided by 0.06 and you get 13,666.6667 which you round to 13,666.67







The first case occurs in

for

and

. Extending the domain to account for all real

, we have this happening for

and

, where

.
The second case occurs in

when

, and extending to all reals we have

for

, i.e. any even multiple of

.