Final answer:
After subtracting the number of rugby balls found by Daniel from the total that should be there, we can determine that 3 rugby balls are missing.
Step-by-step explanation:
The subject of the question is Mathematics and it involves simple subtraction. Daniel found 8 rugby balls but there should be 11. To find out how many are missing, we subtract the number of rugby balls that Daniel found from the total that should be there. Hence, 11 - 8 = 3. Therefore, the number of missing rugby balls is 3.