2(1/3x5 + 1/5x7 + 1/7x9 + 1/9x11+1/11x13)=
=2[(1/3-1/5)/2 + (1/5-1/7)/2 +(1/7-1/9)/2+(1/9-1/11)/2+(1/11-1/13)/2]=
=1/3 - 1/5+1/5 - 1/7+1/7 - 1/9+1/9 - 1/11+1/11 - 1/13=1/3 - 1/13=10/39
35/42+13/42=(35+13)/42=48/42=8/7
59/64 - 19/65=(59 x 65 - 19 x 64)/(64 x 65)=(3^3 x 97)/(2^6 x 5 x 13)
