Gibson company, which produces and sells a small digital clock, bases its pricing strategy on a 25 percent markup on total cost. based on annual production costs for 12,000 units of product, computations for the sales price per clock follow: unit-level costs $ 276,000 fixed costs 60,000 total cost (a) 336,000 markup (a × 0.25) 84,000 total sales (b) $ 420,000 sales price per unit (b ÷ 12,000) $ 35 required gibson has excess capacity and receives a special order for 7,000 clocks for $28 each. calculate the contribution margin per unit. based on this, should gibson accept the special order?