Is this a function ? explain your reasoning.

please help !

A , C, D

Step-by-step explanation:

Check A:

8 - 3 + 4 + 21 = 30         30 > 10 , so they keep the ball

Check B:

30 - 7 - 8 - 12 = 3          3 < 10 , so they don't keep the ball

Check C:

2 + 16 - 5 - 3 = 10         10 = 10 , so they keep the ball

Check D:

5 - 2 + 20 - 1 = 22       22 > 10 , so they keep the ball

Check E:

20 - 3 - 13 + 2 = 6         6 < 10 , so they don't keep the ball

If my answer is incorrect, pls correct me!

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-Chetan K