7/29*3/8+6/29*7/12+3/29*7/9
=7/29*3/8+7/29*6/12+7/29*3/9
=7/29*(3/8+1/2+1/3)
=7/29*(9/24+12/24+8/24)
=7/29*29/24
=7/24
1/3+1/15+1/35+1/63+1/99
=1/1*3+1/3*5+1/5*7+1/7*9+1/9*11
=1/2*(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11)
=1/2*(1-1/11)
=1/2*10/11
=5/11