3 , 5 ( 7 n − 12 ) + 11 n − 12 , 5 3,5(7n−12)+11n−12,5 .

To simplify the expression \( 3.5(7n - 12) + 11n - 12.5 \), we will follow the order of operations:

1. Distribute \( 3.5 \) into \( (7n - 12) \): \[ 3.5 \cdot 7n - 3.5 \cdot 12 = 24.5n - 42 \]

2. Write the expression with the distributed part: \[ 24.5n - 42 + 11n - 12.5 \]

3. Combine like terms:

   • Combine the \( n \) terms: \[ 24.5n + 11n = 35.5n \]
   • Combine the constant terms: \[ -42 - 12.5 = -54.5 \]

4. Thus, the simplified expression is: \[ 35.5n - 54.5 \]

So, the final result is: \[ 35.5n - 54.5 \]