Verified answer

1) 3c + 7c -8c = 10c-8c = 2с

2)16a-5a+7a-11a = 11a -11a +7a = 7a

3)-4t+3t-8-7t = -t - 7t - 8 = -8t-8

4)8x-8y+2y-6x = 8x-6x -8y+2y = 2x -6y

5) 4,5a-7b-1,5a+1 = 4.5a-1.5a -7b +1 = 3a-7b+1

6)-a+3b-4b+1,5a= -a +1.5a +3b-4b = 0,5a -b