William Diesel owns the Fredonia Barber Shop. He employs $5$ barbers and pays each a base salary of $$1,510$ per month. One of the

barbers serves as the manager and receives an extra $$580$ per month. In addition to the base salary, each barber also receives a

commission of $$8\mathrm{.}40$ per haircut.

Other costs are as follows.

William currently charges $$18\mathrm{.}00$ per haircut.

$($a$)$

Determine the unit variable costs per haircut and the total monthly fixed costs. $($Round variable costs to $2$ decimal places, e$.$g$.2\mathrm{.}25.)$

Total unit variable cost per haircut

$

Total fixed costs

$