Anisha, who is a chef at Burnaby Grill Restaurant, needs to find out the variable cost for one of her menu items. She knows that the average selling price of that item is $ $18\mathrm{.}50$ ?and the contribution margin is $ $10\mathrm{.}50.$ ?What is the variable cost percentage $($ rounded $)?$

a $.$

$\mathrm{.}43$

b $.$

$\mathrm{.}57$

c $.$

$43\%$

d $.$

$57\%$