first step is to simplify the equation or calculate..... so the formate of y=mx+b
4y=-5x+12
y=-5/4+3
so slope m=-5/4
b=3
count 3 on the y intercept from zero going up 3,put a dot there . then go down -5 from 3 and then count right 4 and put a dot there.if you need more help ask me or message me.