The answer is: Yes, it is a function. The function is linear.
The explanation is shown below:
1. You must keep on mind the following information: [tex]f(x)[/tex] is a function when for each value of the domain [tex]x[/tex] there is an unique value of [tex]y[/tex]. For example:
[tex]x=2\\y=6[/tex]
2. A linear function has the following form:
[tex]y=mx+b[/tex]
Where [tex]m[/tex] is the slope and [tex]b[/tex] is the y-intercept.
3. When the slope is zero, you have that [tex]y=b[/tex]. Therefore:
[tex]3y-8=4\\y=\frac{12}{3}\\y=4[/tex]
4. As you can see, it is a linear function with [tex]m=0[/tex].
