Riggs Company purchases sails and produces sailboats. It currently produces 1, 200 sailboats per year, operating at normal capacity, which is about 80% of full capacity. Riggs purchases sails at $267 each, but the company is considering using the excess capacity to manufacture the sails instead. The manufacturing cost per sail would be $99.02 for direct $84.23 for direct labor, and $90 for overhead. The $90 overhead includes $78,000 of annual fixed overhead that is allocated using normal capacity. The president of Riggs has come to you for advice. "It would cost me $273.25 to make the sails, she says, but only $267 to buy them. Should I continue buying them, or have I missed something?" (a) Prepare a per unit analysis of the differential costs. (Round answers to 2 decimal places, e.g. 15.25. Enter negative amounts using either a negative sign preceding the number e.g. -45 or parentheses e.g. (45).) Should Riggs make or buy the sails