Answer:
20 bowling balls
Step-by-step explanation:
A hot air balloon would have to have little mass, actually less mass than the air surrounding it in order to be able to float, a canoe ussualy has a mass of around 100 lb, and 30 ounces of lead obviusly are not more than 20 bowling balls, the average mass of a bowling mass is 14 lb, if you multiply that by 20 that is 280 pounds of mass, so the 20 bowling balls have the most mass.