Question

F(x)=3x-8

Answer 1

What this is asking is for you to plug values into the following function:$f(x)=\frac{3x-8}{6x}$

Since the question is asking you to find $f(3)-f(1)$, this is how you work it out:
You take the function;
$f(x)=\frac{3x-8}{6x}$
And plug the numbers indicated in for x;
$f(x)=\frac{3x-8}{6x}\\ f(3)=\frac{3(3)-8}{6(3)}\\ f(3)=\frac{9-8}{18}\\ f(3)=\frac{1}{18}\\\\ f(1)=\frac{3(1)-8}{6(1)}\\ f(1)=\frac{3-8}{6}\\ f(1)=\frac{-5}{6}\\\\ Now\ what\ you\ do\ is\ you\ subract\ f(3)\ and\ f(1).\\ f(3)-f(1)\\ f(3)-f(1)=\frac{1}{18}-\frac{-5}{6}\\ f(3)-f(1)=\frac{1}{18}-\frac{-15}{18}\\ f(3)-f(1)=\frac{1+15}{18}\\ f(3)-f(1)=\frac{16}{18}=\frac{8}{9}$
So the answer to f(3) - f(1) = $\frac{8}{9}$