im not sure if its +9y or -9y but ill use +
-11x + 9y = -12 add 11x to both sides
9y = -12 + 11x. divide all numbers by 9
y = -12/9 + 11/9x. simplify -12 and 9 by 3
y = -4/3 + 11/9x. make sure its in slope intercept form (y=mx+b)
y = 11/9x - 4/3
slope: 11/9
y int: -4/3