Last month the Financial Times reported that Japanese firm Akagi Nyuguyo was increasing the price of its popular children’s ice cream bar Garigari-kun for the first time in 25 years, from ¥60 to ¥70. Suppose that a 7-11 store typically sold 500 ice cream bars a day, but now expects to sell only 400 bars a day. Assuming a linear relationship between price (p) and quantity demanded (x), write down the linear price-demand function p(x)