To find $f\left(\frac{2}{3}\right)$ for the function $f(x) = 3x - 4$, substitute $x = \frac{2}{3}$ into the function:

$f\left(\frac{2}{3}\right) = 3\left(\frac{2}{3}\right) - 4$

Now, simplify:

$f\left(\frac{2}{3}\right) = \frac{6}{3} - 4 = 2 - 4 = -2$

So, $f\left(\frac{2}{3}\right) = -2$.

Would you like more details or have any questions?

Here are five related questions:

1. What is $f(1)$ for the function $f(x) = 3x - 4$?
2. How would you find the inverse of the function $f(x) = 3x - 4$?
3. What is the slope of the function $f(x) = 3x - 4$?
4. How does the function change if the constant $-4$ is replaced with $+2$?
5. What is the value of $f(-1)$ for the function $f(x) = 3x - 4$?

Tip: When substituting a value into a function, make sure to follow the order of operations to simplify correctly.