1/3+1/6x=2/7 两边同乘以42得:14+7x=127x=-2x=-2/7
1/2x=2/7x=2/7x2x=4/7
1/6x=2/7-1/31/6x=6/21-7/211/6x=-1/21所以:6x=-21 x=-7/2=-3.5