8 In Problem 7, a fire destroys some chewing-gum factories and the quantity of chewing gum supplied decreases by 40 million packets a week at each price.

a Explain what happens in the market for chewing gum and draw a graph to illustrate the changes in the chewing gum market.

b If at the time the fire occurs there is an increase in the teenage population, which increases the quantity of chewing gum demanded by 40 million packs a week at each price, what is the new market equilibrium? Illustrate these changes in your graph.