The cost of a giving$-$up$-$cash discount under the terms of sale $3/10$ net $30$ is $...($Assume a $360-$day year.$)$

a$.$

$118\mathrm{.}68\%$

b$.$

$112\mathrm{.}76\%$

c$.$

$55\mathrm{.}67\%$

d$.$

$37\mathrm{.}11\%$