I would like to know how to calculate the preferred dividend if the question has several information :

common shares authorized par value $ 10 100,000
Average common shares outstanding 50,000
8% $100 par preferred atock authorized 80,000
Preferred stock outstanding 30,000

Is it 8% X $100 X 80,000 ? Or 8% X $100 X 30,000 ?

it is the Percentage Rate * stated or Par value of the share* Number of shares Issued and outstanding.