A consumer has $300 to spend on goods X and Y. The market prices of these two goods are Px = $15 and Py = $5.

a/ What is the market rate of substitution between goods X and Y?

b/ Illustrate the consumer's opportunity set in a carefully labeled diagram.

C/ Show how the consumer's opportunity set changes if income increases by $300. How does the $300 increase in income alter the market rate of substitution between goods X and Y?