Ответ:\(2m-6m=-4m\);\(-3c+5c=2c\);\(7d-4d=3d\);\(10k-11k=-k\);\(-8p+9p=p\);\(-4n+3n=-n\);\(6x-10x=-4x\);\(-20y+30y=10y\);\(15e-14e=e\);\(t-2t=-t\);\(6b-8b+b=-b\);\(-3a-a-7a=-11a\);\(-5k-k+9k=3k\);\(x+x+x-4x=-x\);\(-c-c-c-c=-4c\).