8/9 - 2/3 = 8/9 - 6/9 = 2/9 of a pound left
She had 8/9 of a pound of birdseed to begin with. She used 2/3 of a pound of birdseed into her feeders. You have to get a common denominator, would be 9 and when you subtract what she used from what she had you get 2/9 of a pound of birdseed left.
