I'll presume the slash is the fraction bar and the questioner is asking about

That always equals 4 except when 
So the restriction is
Answer: a ≠ -3
Answer:

Step-by-step explanation:
So we want to make x the subject of the formula:

First, distribute the left side:

Combine all the terms with x with it on one side. To do this, first subtract bx from both sides. The right side cancels:

Remove the -ab from the left. Add ab to both sides. The left side cancels:

Now, distribute out the x from the left side:

Divide both sides by (a-b). The left side cancels:

Therefore:

The slope-intercept form:
y = mx + b
m - slope
b - y-intercept
Answer:
B. y = 4/9x + 4
slope = 4/9, y-intercept = 4
D. y = -4/9x - 4
slope = -4/9, y-intercept = -4