Problem 7. It is known that the number of concert tickets demanded is 300 when the ticket price is 50 euros and 200 when the price is 60 euros.

(a) Assuming that demand is a linear function of price, determine the equation of the demand function

(b) Use the equation to calculate the change in demand when the price

(i) increases by 5 euros,

(ii) decreases by 7 euros.