Final answer:
The discount Mrs. Alacon received is 40%.
Step-by-step explanation:
To find the percent discount, we can use the formula:
Discount = (Original Cost - Sale Price) / Original Cost x 100%
Substituting the given values, we get: Discount = ($100 - $60) / $100 x 100% = $40 / $100 x 100% = 0.4 x 100% = 40%
Therefore, the discount Mrs. Alacon received when buying the sweater is 40%.