The given function f(x) is:
[tex]f(x)=3x-2[/tex]Let's start finding f(4) by replacing x=4:
[tex]\begin{gathered} f(4)=3\cdot4-2 \\ f(4)=12-2 \\ f(4)=10 \end{gathered}[/tex]Now, find f(4+h) by replacing x=4+h:
[tex]\begin{gathered} f(4+h)=3\cdot(4+h)-2 \\ f(4+h)=12+3h-2 \\ f(4+h)=10+3h \end{gathered}[/tex]Thus:
[tex]\begin{gathered} \frac{f(4+h)-f(4)}{h}=\frac{10+3h-10}{h} \\ \Rightarrow\frac{3h}{h} \\ \text{Simplify h/h} \\ \frac{f(4+h)-f(4)}{h}=3 \end{gathered}[/tex]The answer is option b. 3