Answer: 2244

Explanation:1. Let $A = (x-3)$ and $B = 8(y+9)$. The system becomes: 1) $A - B = 129$ 2) $A + B = 432$

2. Solve for $A$: Add the two new equations: $(A - B) + (A + B) = 129 + 432$ $2A = 561$ $A = \dfrac{561}{2} = 280.5$

3. Substitute back $A = (x-3)$: So, $x-3 = 280.5$.

4. Calculate the required value $8(x-3)$: The question asks for the value of $8(x-3)$. Since $x-3 = 280.5$, $8(x-3) = 8 \times 280.5$ $8 \times 280.5 = 8 \times \dfrac{561}{2} = 4 \times 561 = 2244$

5. Conclusion: The value of $8(x-3)$ is $2244$.