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5: 1/2+1/3 = 3/6+2/6 =5/6 1/9+1/10 =10/90+9/90 =19/90 1/4+1/7 =7/28+4/28 =11/28 1/5+1/8 =8/40+5/40 =13/40 1/2－1/3 = 3/6－2/6 =1/6 1/9－1/10 =10/90－9/90 =1/90 1/4－1/7 =7/28－4/28 =3/28 1/5－1/8 =8/40－5/40 =3/40 6： 1/10 、 2/25 接近0 4/7、9/20、7/15 接近1/2 8/10、11/13 接近1 7： 4/5+2/3 =12/15+10/15 =22/15 1/10+3/7 =7/70+30/70 =37/70 2/9+1/3 =2/9+3/9 =5/9 5/8--1/5 =25/40--8/40 =17/40 3/5--1/2 =6/10--5/10 =1/10 1--1/9=8/9 8： ① 2/5+4/5=6/5 ② 4/5--2/5=2/5 9： ① 青菜 3/10 番茄 1/5 胡萝卜 1/6 黄瓜 1/3 ② 3/10+1/3 =9/30+10/30 =19/30 ③ 1/5+1/6 =6/30+5/30 =11/30 | 