Срочно??!!!!!!!!!!!!
14/21=2/3 13/39=1/3 24/36=2/3 17n/51n=1n/3n
3/14 и 5/21 9/42 и 10/21 14=7*2 21=7*3 7*3*2=42 5/72 и 7/90 25/360 28/360 72=3*2*2*2*3 90=3*3*2*5 3*2*3*5*2*2=360
а)3/8 и 2/5
3/8 < 2/5
3/8 < 2/5 =15/40 < 16/40
б)4/13 и 2/7
4/13 > 2/7=28/91 > 26/91
3.(4 2/7-3 1/14)+(1 1/28 - 3/14)=4+8/28+1+1/28-3-2/28-6/28=5+9/28-3-9/28=2
4.3 2\5-х-1 1\4=1 1\12
Х=2:/5-1 1/4-1 1/12 Х=2/5-2 4/12 Х=2/5-2 1/3 Х=-1 14/15