Contribution margin

Sally Company sells $21,000$ units at $$11$ per unit. Variable costs are $$6\mathrm{.}38$ per unit, and fixed costs are $$55,300.$

Determine $($a$)$ the contribution margin ratio, $($b$)$ the unit contribution margin, and $($c$)$ operating income.

a$.$ Contribution margin ratio $($Enter as a whole number.$)$

$\%$

b$.$ Unit contribution margin $($Round to the nearest cent.$)$

$

per unit

c$.$ Operating income