直接展开，去括号计算
(n-3m+2)-(4m-2n+1)
=n-3m+2-4m+2n-1
=(n+2n)-(3m+4m)+(2-1)
=3n-7m+1
回答2：
(n-3m+2)-(4m-2n+1)
=n-3m+2-4m+2n-1
=(n+2n)-(3m+4m)+(2-1)
=3n-7m+1
(n-3m+2)-(4m-2n+1)
最佳答案回答1：直接展开，去括号计算(n-3m+2)-(4m-2n+1)=n-3m+2-4m+2n-1=(n+2n)-(3m+4m)+(2-1)=3n-7m+1 回答2：(n-3m+2)-(4m-2n+1)=n-3m+2-4m+2n-1=(n+2n)-(3m+4m)+(2-1)=3n-7m+1
直接展开，去括号计算
