2a-5b+4c-7a+5a+5b-4c
4a+6a+3k-2c+3k+5c-7a
3b-6c+4c-3a+4b
3b+3c-6a+8b-7c-2a
6b-4a+6c+7a-6a+7b-3c-6b
5z+3c+7b-3c-7z-6c+4b
5b+2c-7b+4z-3z-7c
2x-3c-6c-5a+2c-x+4c+6a-x
-2c+3c+7b-2z-5b+2z
2c-4s-6s+6c-2s
5c-6c-7c-8c+2b-6b+9b+7c
-3c+8b-5z+8b-4c
5z-5b+6b-2z-3a+9a-3a
2z+5c-7z+8b-3a
3c-7b+5z-7b+4a-6n+8b-3v+9n-7v
我一共给你凑了15道题哈