Answer:
Here,
denotes the additional cookies that need to be made by Walter besides 15 cookies made by him so far
Explanation:
Number of cookies made by Walter so far = 15
He is asked by his coach to make at least 20 cookies but no more than 55.
Let
denotes the additional cookies that need to be made by Walter besides 15 cookies made by him so far.
The inequality is

Now solve this inequality.
