Вычислите
4/5*5/7 8/9*3/5 9/2*2/9 8/21*7/10 8/15*25/28

3/7*2 3*1/6 9*5/6 2/5*15 1/4*4 5*1/5

2 1/3*2 4*1 1/2 1 1/3*9 3/7*2 1/3 1 1/3*1 1/2

4/5*5/7=4/7; 8/9*3/5=8/15; 9/2*2/9=1; 8/21*7/10=4/15; 8/15*25/28=10/213/7*2=6/7; 3*1/6=1/2; 9*5/6=7 целых 1/2; 2/5*15=6; 1/4*4=1; 5*1/5=1;2 1/3*2=7/3*2/1=14/3=4 2/3 4*1 1/2=4/1*3/2=12/2=6 1 1/3*9=4/3*9/1=12 3/7*2 1/3 =3/7*7/3=11 1/3*1 1/2=4/3*3/2=2