 We may arbitrarily assign the mass of point formula_37 to be formula_69.By ratios of lengths, the mass at formula_39 must be formula_71 and the mass at formula_40 is split formula_73 towards formula_37 and formula_75 towards formula_39.By summing masses, we get the masses at formula_34, formula_23, and formula_26 to be formula_69, formula_81, and formula_82, respectively.