Question 990302

 {{{f(x) = 3x-1}}}

first find {{{f(x-1)}}} and {{{f(2)}}}: 

{{{f(x-1) = 3(x-1)-1}}}

{{{f(x-1) = 3x-3-1}}}

{{{f(x-1) = 3x-4}}}


 {{{f(2) = 3*2-1}}}

 {{{f(2) = 6-1}}}

 {{{f(2) = 5}}}

then you have:

{{{f(x-1) - f(2)=3x-4 -5}}}

{{{f(x-1) - f(2)=3x-9}}}