Give the step-by-step reasoning process and then the final answer. Roxanne bought 2 cups of lemonade for $2 each and 2 sandwiches for $2.50 each. How much change must she get from a $20 bill?
Two cups of lemonade amount to $2 x 2 = $4. Two sandwiches amount to $2.50 x 2 = $5. So, the total amount that Roxanne had to pay was $4 + $5 = $9. Thus, her change must be $20 - $9 = $11.
The final answer: 11.