Find $(g-f)(x)$ when $f(x)=2 x-4$ and $g(x)=5 x-9$

Step 1 ：Given functions are $f(x)=2x-4$ and $g(x)=5x-9$

Step 2 ：We need to find $(g-f)(x)$ which is $g(x) - f(x)$

Step 3 ：Subtract $f(x)$ from $g(x)$ to get $(g-f)(x)$

Step 4 ：So, $(g-f)(x) = (5x-9) - (2x-4)$

Step 5 ：Simplify to get $(g-f)(x) = 3x - 5$

Step 6 ：\(\boxed{(g-f)(x) = 3x - 5}\)