To determine whether the sum of \( \sqrt{25} \) (which simplifies to 5) and 18 is rational or irrational, we first simplify the expression:
\[ \sqrt{25} + 18 = 5 + 18 = 23. \]
Since both \( \sqrt{25} \) (which is a rational number) and 18 (which is also a rational number) are being summed, the result (23) is also a rational number.
The correct response is:
Rational, because both addends are rational.