题目0.3g/ml0.3g/ml0.3g/ml的蔗糖溶液是生物课堂上的常用试剂,该试剂可利用0.75g/ml0.75g/ml0.75g/ml的蔗糖溶液40ml40ml40ml加入xmlx mlxml蒸馏水稀释而成,由题意可列方程（ ）A.40×0.3=0.75x40\times 0.3=0.75x40×0.3=0.75xB.40×0.75=0.3x40\times 0.75=0.3x40×0.75=0.3xC.40×0.7540+x=0.3\frac{40×0.75}{40+x}=0.340+x40×0.75=0.3D.40×0.340+x=0.75\frac{40×0.3}{40+x}=0.7540+x40×0.3=0.75知识点：由实际问题抽象出一元一次方程章节：未标注
