Each successive number is "two times three less" means "six less"

__Answer:__

1. 0, -6, -12, -18, -24, -30 Common difference: d = -6

2. 3, -3, -9, -15, -21, -27

3. 30, 24, 18, 12, 6, 0

You can choose a starting point so that the first 5 numbers in your sequence are all positive just by choosing a integer greater than 24 just enough for positive numbers in the continuing squence.

--7H3_5H4D0W