Final answer:
Harper, having sold 3 cups of lemonade for $9, earns $3 per cup. After selling 6 cups, Harper will have made a total of $18.
Step-by-step explanation:
The subject of this question is Mathematics, and it falls under the category of proportional relationships which is generally a middle school topic.
If Harper earned a total of $9 by selling 3 cups of lemonade, and the relationship is directly proportional, then for every cup of lemonade sold, Harper earns $3 ($9 ÷ 3 cups = $3 per cup).
To find out how much Harper will have made after selling a total of 6 cups of lemonade, we calculate:
- $3 per cup × 6 cups = $18
Therefore, after selling 6 cups of lemonade, Harper will have made $18 in total.