5q+9=-12
first you want to get the variable on a side by itself so your first step is to...
5q+9=-12
     -9  -9
You subtract the the nine from the side with the variable so that the variable will be secluded.  There is a rule though, what you do to one side, you must do to the other, so you add the -9 to the -12, and you get...
5q=-21

Now all you have left to do is figure out what "q" equals. To do this, you must divide both sides by the number next to the variable...

5q=-21
5      5

  After you divide your equation will look like...

q=- 4.2

V²  =U²  + 2as    :U <---  what we want to find
 

   the first step is to subtract the "2as"
 

V²  =U²  +2as<------these cancel each other out....
               -2as

  but...what yout do to one side, you have to do to the other side...so you add the the -2as to the other side
 

V²  - 2as =U² 
 

  to undo a square root, you must divide by it...
 

V² - 2as= U²
 
 

if you have the problem...

containing (-2,4) and having a y-intercept of 8

what you want to do is take the information that you have and make it into an equation...

since we have one set of points and a y intercept, we are going to take the information and put it into point slope form...y-y₁ =x₁ (x+y-intercept)...the equation will like...

_y-4=-2(x+8)

_{this is the final answer...but when you solve you can put the equation into slope-intercept form (y=mx+b)...}
 after solving ( distrubute the 2, and add the 4 to the other side) you will have the equation

y=-2x-12