-5a+(3a-2)-(3a-7)=?
问题描述:
-5a+(3a-2)-(3a-7)=?
答
-5a+(3a-2)-(3a-7)
=-5a+3a-2-3a+7
=-5a+3a-3a-2+7
=-5a+5
=5-5a