2/5+5/6+5/7+7/10+8/15+10/20+12/35
=2/5+1/2+1/3+5/7+1/5+1/2+1/3+1/5+1/2+1/7+1/5
=(2/5+1/5+1/5+1/5)+(1/3+1/3)+(1/2+1/2+1/2)+(1/7+5/7)
=1+2/3+3/2+6/7