Solution
= Solution
The “same age” <binary relation> is a <Euclidean relation>, with age understood as one consistently measured value at a fixed time. If $x$ has the same age as both $y$ and $z$, the ages of $y$ and $z$ are equal. Hence
$$
\boxed{\text{same age is Euclidean}.}
$$
This is another instance of equality of the values of a <function> inducing an <equivalence relation>.