if there is one dot to the right that is far away and 3 dots to the left that are close to the like, estimated distance of the right dot would be 3 and the total distance sum of each dot to the left is 3, so the line would be between the 1 right dot and 3 left dots
Ok the answer of 6 are 12, 18, 24, 30, 36, 42, and 48. The multiples of 9 are 18,27,36,45,54,63,72,81,90,99,108,117,126,135,144,153,162,171,180,189,198,. Hope it helps!