The 5th graders want to raise money for their overnight camping trip by selling cornbread during the school Chili Cook-Off contest. All the pans of cornbread are square. A pan of cornbread costs $12. The customers can buy any fractional part of a pan of cornbread and pay that fraction of $12. For example, 12 of a full pan costs 12 of $12. Mrs. Farmer buys cornbread from a pan that is 14 full. She buys 13 of the remaining cornbread in the pan.
What fraction of the whole pan of cornbread does she buy?