A firm is offered payment terms of $3/15$ net $60$ by a supplier. Calculate the cost of giving up the cash discount. Assume a $365$ day year.

a$.$

$15\mathrm{.}05\%$

b$.$

$113\mathrm{.}00\%$

c$.$

$25\mathrm{.}09\%$

d$.$

$18\mathrm{.}81\%$