ANSWER:
13 years old
STEP-BY-STEP EXPLANATION:
Let x be Devaugn's age and y be Sydney's age.
We establish the following linear equation system:
[tex]\begin{gathered} x=3y \\ x+y=52 \end{gathered}[/tex]We solve the first equation in the second equation:
[tex]\begin{gathered} 3y+y=52 \\ 4y=52 \\ y=\frac{52}{4} \\ y=13 \end{gathered}[/tex]Which means Sydney's age is 13 years old.