阅览室看书的同学中女同学占3/5从阅览室走出4名女同学后看书的同学中女同学占5/9原来阅览室里一共

2个回答

  • 4÷ (3/2 - 5/4)÷(1 - 3/5)

    = 4 ÷ 1/4 ÷ 2/5

    = 16÷ 2/5

    = 40 人