How do you solve slope intercept form

Slope intercept form is
Y=Mx+b
X = slope
B = y-intercept
It depends on what kind of information you have

First you have to take the two x from each value, like this:
-(3,4) and (1,2)
- the you have to plug in the points in the equation, (i suppose that you already know the equation), like this:
-where you see x1 you plug in the first value, in this case is 3. Then you plug in 1 in x2. Ending up with 3-1.
-Then you plug in 4 in y1 and 2 in y2.
-Ending up with the 3-1/4-1. Then you have to solve both substractions. 3-1 is 2 and 4-1 is 3.
-So your slope is 2/3. 
I hope you understood it.