so the y intercept/b is 5 because it wouldn't be -5 because if it was -5 the equation would look like y=4x+5 because if the y intercept was -5 and the equation is subtracting it wuld be adding because when you have 2 - signs it turn into + sign so your answer is 5
and it wouldnt be 4 or -4 because the y intercept is b in the slope form (y=mx+or-b) and b=5 so you can automatically cross them out!