Respuesta :

Answer:

21

Step-by-step explanation:

24 - 18 = 6

6/2 = 3

18 + 3 = 21

Answer: 21

Step-by-step explanation:

18, 19, 20, 21, 22, 23, 24

1     2    3         3     2    1

21 is in the middle

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