Final answer:
Anne calculated a sum of 111 and Adam calculated a sum of 108. The difference between the sums is 3.
Step-by-step explanation:
To find the sum that Anne calculated, we need to know the biggest two-digit number divisible by 3 and the smallest two-digit number divisible by 3. The biggest two-digit number divisible by 3 is 99 and the smallest two-digit number divisible by 3 is 12. So Anne calculated 99 + 12 = 111.
To find the sum that Adam calculated, we need to know the biggest two-digit number not divisible by 3 and the smallest two-digit number not divisible by 3. The biggest two-digit number not divisible by 3 is 98 and the smallest two-digit number not divisible by 3 is 10. So Adam calculated 98 + 10 = 108.
To find the difference between the sums calculated by Anne and Adam, we subtract Adam's sum from Anne's sum: 111 - 108 = 3.