Answer:
first line: 0, 4
explanation: middle of -12 and 12 is 0, then 12/3 = 4
second line: -9, 6
explanation: split into 4 sections per each 12 so 12/4 is 3 and the location of the first unknown point is one section away from 12 so we know the distance between there is 3, leaving -12+3 = -9. Then two sections less than 12 is 12-6 = 6
third line: -12, 4
explanation: 24/6 = 4, -24 + 12 = -12 so 4 units each sections 0 + 4 = 4
