Final answer:
The missing number in the sequence is 54.
Step-by-step explanation:
The missing number in the sequence is 54.
To identify the missing number, we need to observe the pattern in the sequence. The sequence decreases by 12 each time. Starting from 78, we subtract 12 to get 66, then subtract 12 again to get 54, and so on. Therefore, the missing number is 54.
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