Formula for Average Cost in the Price-Setting Model

In a model where labor is the only production cost, the average cost (AC) is initially expressed as the total wage bill (Nominal Wage 'W' times Number of Workers 'N') divided by total output ('Y'), giving the formula $AC = \frac{WN}{Y}$. If labor productivity ('λ') is defined as output per worker, or $\lambda = \frac{Y}{N}$, which of the following statements best explains the mathematical step that simplifies the average cost formula to $AC = \frac{W}{\lambda}$?

A firm's production process uses only labor as an input, and labor productivity is constant. Arrange the following statements to show the logical derivation of the simplified average cost (AC) formula, starting from its basic definition.

Simplifying Average Cost Calculation

Analyzing a Flawed Derivation