Answer: See explanation
Step-by-step explanation:
Let the possible number of CDs that she could buy be represented by x. Then, the equation can be represented as:
80 - 18x ≤ 20
80 - 20 ≤ 18x
60 ≤ 18x
x ≤ 60/18
x ≤ 3.33
The highest amount of cd that she can is 3 or less.