In the month of June, Sheridan Hebert's Beauty Salon gave $4,000$ haircuts, shampoos, and hair colorings at an average price of $$45.$ During the month, fixed costs were $$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

$

$

$$

$$