Same Zifference

Normal sudoku rules apply. Ziffer lines are Zipper lines with a difference! Along a Ziffer line, each pair of digits that are the same distance from the line's central spot have the same difference. This difference value appears on the line's central spot.

Eg: if the centre digit of a Ziffer line is a 3, then each pair of digits that are the same distance from that central spot have a difference of 3.

Digits separated by the black dot are in a 1:2 ratio (one is double the other.)