Combine like terms: add and subtract the coefficients of \(u\).<br><br>
&bull; \(u\) means \(1u\)<br>
&bull; \(11u - u - 5u = 11u - 1u - 5u\)<br>
&bull; \(11 - 1 - 5 = 5\), so the result is \(5u\)<br><br>
Final Answer: C: \(5u\)