二分之x+y-三分之x-y=六分之五① 六分之x+y-三分之x-y=二分之一②解方程组

(x+y)/2-(x-y)/3=5/6 ①(x+y)/6-(x-y)/3=1/2 ②①②等号两边分别同时乘以6去分母得：3(x+y)-2(x-y)=5(x+y)-2(x-y)=3 令(x+y)=a,(x-y)=b得：3a-2b=5 (3)a-2b=3 (4)(3)-(4)得：2a=2,a=1代入(4)解得：b=-1那么,x+y=...