1)=2m-2+2m=4m-2
2)=5m+15n+4m-2n=9m+13n
3)=3x+6y+8x-4y=11×+2y
4)=14x+21y-9×-6y=5×+15y
5)=30c+15d-9c-18d=21c-3d
6)=10c+8d-8c-10d=2c-2d
1)=2m-2+2m=4m-2
2)=5m+15n+4m-2n=9m+13n
3)=3x+6y+8x-4y=11×+2y
4)=14x+21y-9×-6y=5×+15y
5)=30c+15d-9c-18d=21c-3d
6)=10c+8d-8c-10d=2c-2d