Give the step-by-step reasoning process and then the final answer. Laura wants to bake a cake for her mother. She checks the recipe and the pantry and sees that she needs to buy 2 cups of flour, 2 cups of sugar, a cup of butter, and two eggs. The flour costs $4. The sugar costs $2. The eggs cost $.5, and the butter costs $2.5. When she is done baking it, she cuts the cake into 6 slices. Her mother enjoys a piece the first two days. But on the third day, they discover that Kevin, her dog, ate the rest of the cake. How much did the amount the dog ate cost?
The cake cost $9 in total because 4 + 2 + .5 + 2.5 = 9. Each slice costs $1.5 because 9 / 6 = 1.5. The dog ate 4 slices because 6 - 2 = 4. The amount the dog ate cost $6 because 4 x 1.5 = 6.
The final answer: 6.