Suppose that you can sell as much of a product (in integer units) as you like at $68 per unit. Your marginal cost (MC) for producing the qth unit is given by: MC = 9q. This means that each unit costs more to produce than the previous one (e.g., the first unit costs 9*1, the second unit (by itself) costs 9*2, etc.). If fixed costs are $60, what is the optimal output level?