Using x skilled workers and y unskilled workers, a manufacturer can produce Q(x, y) = 10x²y units per day. Currently there are 20 skilled workers and 40 unskilled workers on the job.

a. How many units are currently being produced each day?

b. By how much will the daily production level change if 1 more skilled worker is added to the current workforce?

c. By how much will the daily production level change if 1 more unskilled worker is added to the current workforce?

d. By how much will the daily production level change if 1 more skilled worker and 1 more unskilled worker are added to the current workforce?