The first 8 customers bought 8 * 3 = 24 cases of cat food.
The next 4 customers bought 4 * 2 = 8 cases of cat food.
The last 8 customers bought 8 * 1 = 8 cases of cat food.
Therefore, the total number of cases of cat food sold is 24 + 8 + 8 = 40 cases.
#### 40
The answer is: 40
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
If there was a sale on cat food at the pet store and 20 people bought cat food that day, with the first 8 customers buying 3 cases each, the next four customers buying 2 cases each, and the last 8 customers buying 1 case each, what is the total number of cases of cat food sold?

### Answer:
