Thinking...
This is a straightforward arithmetic problem. Let me compute step by step.
...done thinking.
**Step-by-step:**
1. **Multiplication:** $17 \times 23$
- $17 \times 20 = 340$, $17 \times 3 = 51$
- $340 + 51 = \mathbf{391}$
2. **Division:** $144 \div 12 = \mathbf{12}$
3. **Addition and subtraction:** $391 + 12 - 89$
- $391 + 12 = 403$
- $403 - 89 = \mathbf{314}$
Answer: 314