What is the undefined value for 22=4+5x/9x−6?

To find the undefined value for the equation \( 22 = \frac{4 + 5x}{9x - 6} \), we need to identify when the denominator equals zero, as that is when the expression is undefined.

The denominator is \( 9x - 6 \). We set this equal to zero and solve for \( x \):

\[
9x - 6 = 0
\]

Adding 6 to both sides gives:

\[
9x = 6
\]

Now, dividing both sides by 9:

\[
x = \frac{6}{9}
\]

We can simplify \( \frac{6}{9} \):

\[
x = \frac{2}{3}
\]

Thus, the undefined value is:

\[
\boxed{\frac{2}{3}}
\]