<span>y=-4/x+1 is ambiguous, since it's not immediately clear whether you meant
-4
y = -4/x + 1 or y = ---------
x+1
I'm going to assume that the latter is what you meant.
1. Interchange x and y, obtaining:
-4
x = --------
y+1
2. Solve this for y, obtaining y+1 = -4/x, or xy + x = -4, or
-x - 4
xy = -x-4, or y = ---------
x
-1 -1 4
3. Replace y with f (x): f (x) = -1 - -----
x
This last result has the correct form.</span>
<span>Solving for the slope using points ( (−4, 15), (0, 5)</span>
M = ( 15 – 5) / ( -4 – 0) = -5 / 2
Solving for b
<span>
Y = mx + b</span>
5 = 0(-5/2) + b
B = 5
So the linear function is
<span>Y = (-5/2) x + 5</span>