In the month of June, Sheridan Hebert's Beauty Salon gave $4,000$ haircuts, shampoos, and hair colorings at an average price of $$4$ During the month, fixed costs were $$18,000$ and variable costs were $75\%$ of sales.

$($a$)$

Determine the contribution margin in dollars, per unit and as a ratio. $($Round contribution margin per unit to $2$ decimal places, e$.$g$.5\mathrm{.}75.)$

Contribution margin

$

Unit contribution margin

$

Contribution margin ratio

$\%$