1) 17ab + 17ab + 17ab = 17ab*(1 + 1 + 1) = 17ab*3 = 51ab.
2) 2m + 2m + 2m = 2m*(1 + 1 + 1) = 2m*3 = 6m.
3) (c - 2d) + (c - 2d) = c - 2d + c - 2d = 2c - 4d.
1) 17ab + 17ab + 17ab = 17ab*(1 + 1 + 1) = 17ab*3 = 51ab.
2) 2m + 2m + 2m = 2m*(1 + 1 + 1) = 2m*3 = 6m.
3) (c - 2d) + (c - 2d) = c - 2d + c - 2d = 2c - 4d.