Final answer:
Nia's total cost on a given day is $50.
Step-by-step explanation:
To calculate Nia's total cost on a given day, we need to sum up the fixed costs and the variable costs. The fixed costs are $20 per day. As stated in the question, Nia's only variable cost is labor, with a daily wage of $30 for all workers. Therefore, the variable cost due to labor is $30.
To find the total cost, we simply add the fixed costs and the variable costs:
Total Cost = Fixed Costs + Variable Costs
Total Cost = $20 + $30 = $50
Therefore, Nia's total cost on a given day is $50 (Option A).