Brownsville, Texas, boasts being the southernmost international seaport and the largest city in the lower Rio Grande Valley. Ben Supple, an importer in Brownsville, has just received a shipment of Peruvian opals that he is pricing for sale. He paid $139 for the shipment. Assume he wants a 75% markup. a. Calculate the selling price when the markup is based on selling price. (Round your answer to the nearest cent.) Selling price when the markup is based on selling price b. Calculate the selling price when the markup is based on cost. (Round your answer to the nearest cent.) Selling price when the markup is based on cost