А)1/11+1/5+4/11+4/5+6/11 в)1/15+4/15+1/18+5/18+2/21+5/21+1/24+7/24

1/11 + 1/5 + 4/11 + 4/5 + 6/11 = 5/11 + 5/5 + 6/11 = 11/11 + 5/5 = 1+1 = 2
===
1/15 + 4/15 + 1/18 + 5/18+2/21 + 5/21 + 1/24 + 7/24 = 5/15 + 6/18 + 7/21 + 8/24=
=1/3 + 1/3 + 1/3 + 1/3 = 1   1/3