a-3(-b+c-d)化简
问题描述：
a-3(-b+c-d)化简
就化成字母就行
答
a-3(-b+c-d)
=a+3b-3c+3d
a-3(-b+c-d)化简
就化成字母就行
a-3(-b+c-d)
=a+3b-3c+3d