In order to find the firms demand for labor you havr to solve the profit maximization problem that the firm faces, the problem can be dexcribed mathematically in your example with the following formulas,
[tex]Maximize PQ-wL \\ subject \; to \\ f(L)=q=2L[/tex]
Solving this problem will result to a function that relates the amount of labour (L) with wage(w)
