Susan makes delicious cupcakes. Due to her success, she can set the price in the market for her cupcakes. The inverse market demand for cupcakes is represented by = 100 , while the marginal cost of her cupcakes is R10.

a) Calculate and graph the equilibrium price and quantity. Your diagram needn't be perfectly to scale if the important points are labelled correctly. (Make use of the MR=MC approach for this question) [6]

b) Calculate and interpret the consumer and producer surplus, as well as the deadweight loss at equilibrium. [6]

c) Calculate the slope of the Isoprofit curve when she sells 40 cupcakes. [2]

d) Calculate the slope of the demand curve when she sells 40 cupcakes. [2]

e) Explain how you can use your answers to c) and d) to find the equilibrium quantity of cupcakes in this market. [4]

f) Show that the Isoprofit method gives the same equilibrium found in a). [4]