please answer with good explanation

On July 1, 2021, Gameshop Corp., repurchased 2,000 shares of its outstanding common shares for $18 per share. Prepare journal entries for the transaction under each of the following independent assumptions: (1) The average cost of previously issued common shares was $20 per share; 2 The average cost of common shares previously issued was $10 per share and contributed surplus of $20,000 existed with respect to earlier common share repurchases; (3) The average cost of common shares previously issued was $10 per share and contributed surplus of $5,000 existed with respect to earlier common share repurchases