Total labor costs have surged, sparking a fierce debate between the HR and Finance departments. HR claims the company hired too many people, while Finance blames massive, uncontrolled wage hikes. Students will use a two-factor model (Total Cost = Headcount × Average Wage) to mathematically resolve this corporate dispute. 

Roadmap to Solution:

Step 1: Establish the sequence. Remember the iron rule: quantitative factors (Headcount, Z) always come before qualitative factors (Average Wage, W).

Step 2: We need to calculate the financial impact caused strictly by the change in Average Wage (ΔF_W).

Step 3: Since Wage is the second factor, the Headcount factor (Z) has already been updated in the chain. Use the new, actual headcount (Z₁).

Step 4: Calculate the difference in the average wage (W₁ - W₀).

Step 5 (Wage Impact): Multiply the actual headcount by the wage difference: Z₁ × (W₁ - W₀).