(x+y)/6+(x-y)/10=3 ①(x+y)/6+(y-x)/10=-1 ②①可变为：(x+y)/6-（y-x)/10=3 ③②+③=(x+y)/3=2得x+y=6 ④②-③=（y-x）/5=-4得y-x=-20 ⑤④+⑤=2y=-14得 y=-7④-⑤=2x=26得x=13
