Answer the following question.
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?
Step-by-step reasoning process: 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 answer is 11.

Answer the following question.
Allie's making guacamole for a party. Each batch requires 4 avocados and serves about 6 people. If 42 people are going to be at the party including her, how many avocados does she need?
Step-by-step reasoning process: Each batch serves 6 people, and there are 42 people coming to the party, so she needs to make 42 / 6 = 7 batches. Each batch requires 4 avocados, so she will need 4 * 7 = 28 avocados.
The answer is 28.

Answer the following question.
John paints a giant mural that is 6m by 3m. The paint costs $4 per square meter. The artist can paint 1.5 square meters per hour and charges $10 per hour. How much does the mural cost?
Step-by-step reasoning process: The mural is 6 * 3 = 18 sq meters. So the paint cost 18 * 4 = $72. The artist works for 18 / 1.5 = 12 hours. He charges 12 * 10 = $120. So the total cost is 120 + 72 = $192.
The answer is 192.

Answer the following question.
Brittany got a 78 on her first test. After her second test, her average rose to an 81. What grade did she get on her second test?
Step-by-step reasoning process: First multiply her average grade by the number of tests she took to find the total number of points she scored: 81 points * 2 = 162 points. Then subtract the number of points she scored on her first exam to find how many points she scored on her second exam: 162 points - 78 points = 84 points.
The answer is 84.