Ok so ideally we would like to see this in y=mx+b form. But it will take some algebreic skills to ninja our way through this.
I'll show my steps so you can follow,
3+4x = 2y - 9 (original equation)
Next we just add 9 to both sides,
12 + 4x = 2y, now we can divide both sides by 2,
y=2x+6 as our final equation. This is in y=mx+b form, thus the slope of our line is 2 because the 2 is sitting in the m space of the equation. If you still dont understand linear stuff, I'd google slope-intercept form
