1999 AMC 8 Problem 17

Problems 17, 18, and 19 refer to the following:

At Central Middle School the 108 students who take the 1999 AMC 8 meet in the evening to talk about problems and eat an average of two cookies apiece. Walter and Gretel are baking Bonnie's Best Bar Cookies this year. Their recipe, which makes a pan of 15 cookies, lists these items: 1\frac{1}{2} cups flour, 2 eggs, 3 tablespoons butter, \frac{3}{4} cups sugar, and 1 package of chocolate drops. They will make only full recipes, not partial recipes.

Walter can buy eggs by the half-dozen. How many half-dozens should he buy to make enough cookies? (Some eggs and some cookies may be left over.)

\text{(A)}\ 1 \qquad \text{(B)}\ 2 \qquad \text{(C)}\ 5 \qquad \text{(D)}\ 7 \qquad \text{(E)}\ 15

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.