Do what? You titled the thread, "This is a Linear function", which it is NOT- it is a linear equation-but you haven't said what you want to do with it.
Guessing that you want to solve the equation, I would suggest ,multiplying both sides by (5)(7)= 35 to get rid of those denominators. Doing that you should get 15(5x- 4)= 42(4x+ 3). Now multiply out each side: 75x- 60= 164x+ 123. Can you finish from there?