No wonder you have posted this. It is not easy. Scale is a straight line measurement. You need to use a side of a square.
Left: 1 side of a square = 1 meter.
Center: 3 tops of a square = 1 meter.
Therefore 1 side of a square = 1/3 of a meter.
Right: 1 side of a square = 0.5 meters.
