Divide number of pounds eaten by the portion of the bag eaten.
= 4 1/2 pounds ÷ 3/4
= 4.5 ÷ 0.75
= 6 pound bag
CHECK:
multiply total pounds of bag by portion eaten
= 6 pound bag * 3/4
= 4 1/2 pounds eaten
ANSWER: The bag was 6 pounds of dog food.
Hope this helps! :)