5. Simplify the expression \[ 9 n+18(2 n-6)+13 \]

To simplify the expression \( 9n + 18(2n - 6) + 13 \), start by distributing the \( 18 \) into the parentheses: \[ 18(2n - 6) = 36n - 108. \] Now substitute this back into the expression: \[ 9n + 36n - 108 + 13. \] Next, combine like terms. First, combine the \( n \) terms: \[ 9n + 36n = 45n. \] Now combine the constant terms: \[ -108 + 13 = -95. \] Putting it all together, you have: \[ 45n - 95. \] So, the simplified expression is \[ \boxed{45n - 95}. \]