Solution: If there are X people in the chorus, there are (150-X) people in the wind band, and x-50=2/3×( 150-x) solution: If x=90, there are 90 people in the chorus and 60 people in the wind band. I don't think the 50 people who transferred from the chorus were transferred to the wind band because it was not mentioned in the title. This is just my opinion, you can have a look.