BP makes a variety of ceramic sinks and tubs. EBP has just developed a line of sinks and tubs made from a mixture of glass and ceramic. The sinks sell for $150 each and have variable costs of $80. The tubs sell for $600 and have variable cost of $450. The glass and ceramic sinks and tubs require the use of specialized molding equipment. The specialized molding equipment has 4,050 hours of capacity per year. A sink uses an average of 2 hours of specialized molding equipment time; a tub uses an average of 5 hours of specialized molding equipment time.What is the contribution margin per hour of specialized molding time for tubs?