4. Calculating the marginal rate of substitution (MRS) Raphael likes to eat donuts and popsicles. The following graph plots one of Raphael's indifference curves (I1), which shows his monthly preferences for donuts and popsicles. Complete the following table by determining Raphael's marginal rate of substitution (MRS) between the two points listed in each row. (Note: Although the MRS is technically always negative, enter a positive number in the following table since it asks for the amount of popsicles per donut that represents Raphael's MRS.).