Data Sufficiency (DS) | Re: A customer eats the lunch special at a restaurant and adds a tip

A customer eats the lunch special at a restaurant and adds a tip of 15 percent to his bill. What was the total cost of the lunch, including the tip?

1) If the customer had left no tip, he would have paid $8.00 for the lunch.
2) The total cost of his lunch, including the tip, was 80 percent of the cost of the same meal at dinnertime, which is $11.50.