Question

How to rewite this x+4y=-4 in form y=mx+b

Answer 1

So  if you want y=mx+b

you subtract x from both sides and get
4y=x-4
divide both sides by 4
y=(1/4)x-1 or y=(1/4)x+(-1)

Answer 2

$x+4y=-4\\ 4y=-x-4\\ y=-\frac{1}{4}x-1$