Answer
9 less than the quotient of $z$ and 8.
Work Step by Step
The quotient of $z$ and 8 expresses the division of $\frac{z}{8}$.
"9 less than" expresses that 9 is being subtracted from that term.
Therefore, $\frac{z}{8}-9$ can be expressed as "9 less than the quotient of $z$ and 8."