Answer
$18$
Work Step by Step
To find the value of $y$ in the given function when $x=6$, substitute $6$ to $x$ to obtain:
$y=4x-6
\\y=4(6)-6
\\y=24-6
\\y=18$
Thus, the given function includes the ordered pair $(6, 18)$.
Therefore, the missing expression in the given statement is:
$18$.