Combine like terms: add the coefficients of \(y\).<br><br>
&bull; \(4y\) and \(9y\) are like terms (both have the variable \(y\)).<br>
&bull; \(4 + 9 = 13\), so \(4y + 9y = 13y\)<br><br>
Final Answer: A: \(13y\)