Barnes Company reports the following for its product for its first year of operations.

Direct materials

Direct labor

Variable overhead

Fixed overhead

Variable selling and administrative expenses

Fixed selling and administrative expenses

$$30$ per unit

$$20$ per unit

$$10$ per unit

$$80,000$ per year

$$2$ per unit

$$32,000$ per year

The company sells its product for $$140$ per unit. Compute contribution margin using variable costing assuming the

company $($a$)$ produces and sells $2,500$ units and $(b)$ produces $3,200$ units and sells $2,500$ units.