1/11+14/15+17/21+34/35+37/56+87/88
=1/11+1-1/88+1-1/15+1-4/21+1-1/35+1-19/56
=5+7/88-1/5(1/3+1/7)-4/21-19/56
=5+7/88-1/5*10/21-4/21-19/56
=5+7/88-2/7-19/56
=5+7/88-5/8
=5-6/11
=49/11