Claire has two bags of compost to use in her garden. One bag holds cubic feet of compost, and the other bag holds cubic feet of compost. Claire makes a mistake when she follows these steps to estimate about how much compost, in cubic feet, she has. Step 1: Write an equation. Use c to stand for the unknown amount of compost. Step 2: Replace each fraction with the closest benchmark fraction. Step 3: Rewrite the equation using the benchmark fractions, and solve the equation. Step 4: So, there is about cubic feet of compost in all. In which step did Claire first make a mistake? Which statement explains her mistake? What is the exact total amount of compost Claire has, in cubic feet?