Union Lighting Inc. has been manufacturing its own lamp shades for its table lamps. The company is currently operating at $100\%$ capacity. The direct materials cost is $ $5$ per unit, the direct labour cost is $$6$ per unit and variable manufacturing costs are $40\%$ of direct labour costs. Total fixed manufacturing costs are $$500,000$ per year. Normal production is $50,000$ lampshades per year.

A supplier offers to make the lampshades at a price of $$20$ per unit. If Union accepts the offer all variable manufacturing costs would be $100\%$ avoidable and $$200,000$ of the total fixed manufacturing costs would be unavoidable.

a$)$ Prepare an incremental analysis for the decision to make or buy the lampshades.

b$)$ Should Union make or buy the lampshades? What is the $ advantage?

c$)$ Assume that if Oldman decides to buy the lampshades part of the factory space could be used to produce $10,000$ other lighting products that would generate a contribution margin $$15$ per unit. Should Union make or buy the lampshades? Show your calculations.