Blue Inc. had a rent expense of $4000, salaries expenses $15,000, and utilities expensive $2000 for the period ending December 31, 2019. Blue Inc. also paid out $4000 in dividends during the period, and had a beginning balance in retained earnings of $20,000, and an ending balance in retained earnings of $37,000. What is Blue Incs revenue for the period ended December 31,2019?