## Precalculus (6th Edition)

$18$
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: $18$.