Plymouth Industries incurs the following costs during the current year: $$15\mathrm{.}000$ Depreciation of machinery $6\mathrm{.}000$ Direct labor $4\mathrm{.}000$ Direct materials $20\mathrm{.}000$ Manager salaries $15,000$ Rent on Building $10,000$ Sales commissions Sales for the year were $$80,000$ and Plymouth Industries determined that only the direct production costs $($direct labor and direct materials$)$ and sales commissions direct production costs direct obsts, all other costs are classified as fixed costs. Plymouth sold $400$ units. Required: $(17\mathrm{.}5$ points$)$ a$.$ Calculate the variable costs per unit. b$.$ Calculate the sales price per unit. c$.$ d$.$ Calculate the total fixed cost. Calculate the unit contribution margin and the contribution margin ratio for Plymouth Industries e$.$ Based on the above information, compute the break$-$even point in units for Plymouth Industries. $($notes: round up to one unit$)$