解: 45/15=3×15/15=3 34/17=2×17/17=2 30/20=(3×10)/(2×10)=3/2 9/12=(3×3)/(3×4)=3/4 49/56=(7×7)/(7×8)=7/8 21/7=3×7/7=3祝你开心
45/15 = 334/17 =230/20 = 3/29/12 = 3/449/56 = 7/821/7 = 3
3、2、3/2、3/4、7/8、3