Answer: 46 years old
Step-by-step explanation: If Devaughn is 13 years younger than Sydney,
we can represent Sydney's age as x and Devaughn's age as x - 13.
Since the sum of their ages is 79, we have x + x - 13 = 79.
This simplifies to 2x = 92.
Dividing both sides by 2, we have x = 46.
So sydney is 46 years old.