Whitmore Glassware makes a variety of drinking glasses and mugs. The company$$s designers have discovered a market for a $16$ ounce mug with college logos$.$ Market research indicates that a mug like this would sell well in the market priced at $$28\mathrm{.}21.$ Whitmore only introduces a product if they can an operating profit of $30$ percent of costs.

Required:

What is the highest acceptable manufacturing cost for which Whitmore would be willing to produce the mugs? $($Round your answer to $2$ decimal places.$)$