To simplify the expression \((3x + 4) - (-x - 5)\), start by distributing the negative sign across the second term: \[ (3x + 4) + (x + 5) \] Next, combine like terms: 1. Combine the \(x\) terms: \(3x + x = 4x\) 2. Combine the constant terms: \(4 + 5 = 9\) Putting it all together, we get: \[ 4x + 9 \] So, the simplified expression is: \[ \boxed{4x + 9} \]