Final answer:
Lee's net earnings per month are $4200.
Step-by-step explanation:
To calculate Lee's net earnings per month, we need to subtract the amount of federal and state income tax from his gross salary. If the total income tax is 30% of Lee's gross salary, we can calculate it as 0.3 * $6000 = $1800. Now, we can subtract the income tax from Lee's gross salary to find his net earnings: $6000 - $1800 = $4200.