Lindsay brought x watermelon slices to a party. Caroline brought y watermelon slices. The 7 people at the party each ate the same number of watermelon slices. If Lindsay brought 12 watermelon slices and Caroline brought 9 watermelon slices, how many slices did each person eat?

3. I checked.

Answer: each person ate 3 slices of watermelon.

Step-by-step explanation:

The total number of people at the party was 7.

Total number of watermelon slices that Lindsay brought to the party is 12. Total number of watermelon slices that Caroline brought to the party is 9. Total number of slices that that both of them brought to the party would be

12 + 9 = 21 slices

The 7 people at the party each ate the same number of watermelon slices. It means that the number of slices that each person ate would be

21/7 = 3