Suppose there are two consumers in the market for a good and their demand functions are as follows:    (5 marks)

d1(p) = 20 − p for any price less than or equal to 20 and d1(p) = 0 at any price greater than 20.

d2(p) = 30 − 2p for any price less than or equal to 15 and d1(p) = 0 at any price greater than 15.

Find out the market demand function.