Answer:The simplified expression that represents the uncle's age is
4y + 12
Explanation:
Let y represent your age.
Your sister is 3 years older than you. This means that your sister's age is y + 3
Your uncle is 4 times older than your sister. It means that the age of your uncle would be
4(y + 3)
The simplified expression that represents your uncle's age would be
4y + 12