well if there are 30 between each base then all the have to do is look at the other sides next to them and go up 30 for the lines in the right
so lets say up down right left if they are all 30 long and your on the up and you need to go down 30 in then you will look over at the lines of the right side and go down 36 in then you will be 36 inches closer down
if that makes scene have a good day/night