you need to get y by itself so do the inverse operation of adding to subtracting 2x to go on the other side
2x - 6y = 12 => -6y = -2x + 12
since you subtracted 2x it's now a negative
then you divide 6 from y to get 'y' by itself and also simplify -2x and 12
[tex] \frac{ - 6y}{ - 6} = \frac{ - 2x}{ - 6} + \frac{12}{ - 6} [/tex]
from there y is by itself and divided
y = 1/3 x - 2
