The marketing manager of Durant Corporation has determined that a market exists for a telephone with a sales price of $23 per unit. The production manager estimates the annual fixed costs of producing between 42,000 and 81,000 telephones would be $384, 200. Required: Assume that Durant desires to earn a $135,000 profit from the phone sales. How much can Durant afford to spend on variable cost per unit if production and sales equal 47, 200 phones