申論題

4.Jamie's marginal utility from muffins and from doughnuts is shown in the accompanying table. Jamie has $18 in the pocket to allow her to consume muffins and/or doughnuts. The price of each mufin is $3 and the price of each doughnut is $2.

Within the budget, how much does Jamie need to spend on doughnut to optimize her consumption expenditure?___________