Answer :
120 movie posters
100 band posters
Movie:band=120:100=24:x
120/100=6/5
6•4=24
5•4=20
Movie:band=24:20
She should sell 20 band posters
100 band posters
Movie:band=120:100=24:x
120/100=6/5
6•4=24
5•4=20
Movie:band=24:20
She should sell 20 band posters