y-1/2y-1=2-(y/5+2)还是y-1/2y-1=2-y/5+2,如果是前边的答案是y=10/7,后者答案是y=50/7是第1种！！！！有答案没算式？y-1/2y-1=2-(y/5+2) 简化为 1/2y-1=2-y/5-2;1/2y-1=-y/5;1/2y-1+y/5=0; 1/2y+y/5=1;等式两边同时乘以10得到5y+2y=10; 7y=10; y=10/7