Answer:
the question is invalid. please rewrite the question.
Answer: 
Step-by-step explanation:
- The equation of the line in the slope intercept form is: 
Where m is the slope and b is the y-intercept of the line
- Let's choose two points of the line: (8,-1) and (-4,-4).
- You must calculate the slope of the line as following:

- As you can see in the graph attached, the line intersects the y-axis at -3, then b=-3.
- Substituting values into the equation of the line, you obtain:

The equation looks like this:
26=x*3.5+8.50
where x is the number of pen you bought.
We solve it like this:
first, we subtract 8.50 from both sides:
17.50 =3.5*x
now we divide both sides by 3.5:
5=x
so you purchased 5 pens.
It’s C! that’s the answer, hope it helps