3分之2+15分之2+35分之2+63分之2+99分之2 =2/3+2/15+2/35+2/63+2/99(乘以最小公倍数5*7*9*11=3465) =2*(5*7*9*11/3+7*9*11/3+9*11+5*11+5*7)/3465 =3150/3465 =630/693 =70/77 =10/11