Verified Answer :

You need to turn this equation....into something that looks like

y = mx + b

*notice the 'y' is by itself on the left side...so how would you get 'y' by itself on the left side in your equation?
alternative :
if given a straight line ax + by = c, then the slope always m = -a/b
Actually, just to make it easier on this exact question...use what RadEn has shown. You have an equation

ax + bx = c

to find the slope.... you do
slope = -a
---
b

So your equation, what is 'a' and what is 'b'?
6x + 8y = 12

The answer is -3/4 because you would subtract 6x from both sides then divide 8 from both sides.