A new electric piano has been made. The materials for a piano total 30 and 2 hours of labour (paid at 15 hhour) are needed to assemble one. Variable overheads are charged at 3/labour hour and the associated fixed costs are 200 per month. If the selling price is set at \&266, how many pianos need to be sold to achieve an annual profit of 32,000? a. 165 units. b. 272 units. c. 172 units. d. 210 units