Find $X$ from the given series:
$64,57,50,X,36,\dots$

Let's analyze the difference between consecutive numbers in the series:
$$57-64=-7$$

$$50-57=-7$$

The series follows a constant pattern where $7$ is subtracted from the previous number. Following this pattern:

$$X=50-7=43$$

Let's verify with the next term:

$$43-7=36$$

This matches the next term in the series perfectly. Thus, $X=43$.