"1: If there is a decrease in the price of a substitute good, does the demand curve for this good shift to the left or to the right? Why?

"1: If there is a decrease in the price of a substitute good, does the demand curve for this good shift to the left or to the right? Why?2:Suppose that consumer spending is 200, and spending on food, transport and leisure is 60, 20 and 10 respectively. Suppose that after five years consumer spending doubles to 400. How much do you believe will be the budget share of leisure? Why?3: Since Ford and Vauxhall are very competitive with one another, should we view them as perfectly competitive firms? Why?