Answer: C. 15 ≤ 2x + 9 ≤ 19
Explanation:
We know that her goal is to knit at least 12 scarves and, at the most, 19 scarves
So it has to be bigger or equal to 15 and smaller or equal to 19, so it can't be A or D.
We also know that she has already knitted 9, so our equation has to have a +9
So the answer is C. 15 ≤ 2x + 9 ≤ 19