2x +1=3x=1代入2-(a-x)/3=06=a-1a=7选A如果满意，请记得采纳，谢谢(*^__^*) 嘻嘻
7
2x+1=32x=2x=1将x=1代入后式2-（a-1）/3=06-a+1=0a=7
