we know that 1 lb = 16 oz
So lets convert the 20 lb to oz and then compare the two quantities in consistent units.
If 1 lb = 16 oz then 20 lb are equal to 20*16 oz, that is
20 lb = 20*16 oz = 320 oz
therefore,
320 oz are greater than 272 oz, or,
20 lb are greater that 272 oz