Use the preceding graph to answer the following questions. a. What is the marginal rate of substitution at 3 concert tickets and 8 movie tickets? b. If the consumer's income decreases by 10% and the price of both goods decrease by 10%, how many concerts and movie tickets will the consumer purchase? c. If the price of movie tickets doubles, what does the marginal rate of substitution equal at the new utility-maximizing point? Concert tickets 8- 7. 6. 5- 4- 8 10 12 14 16 Movie tickets 3.