Du meinst wie du es nach x auflöst?
(4170.97 + 0.73·x)/(4600 + x) = 0.75
4170.97 + 0.73·x = 0.75·(4600 + x)
4170.97 + 0.73·x = 0.75·4600 + 0.75·x
4170.97 - 0.75·4600 = 0.75·x - 0.73·x
4170.97 - 0.75·4600 = (0.75 - 0.73)·x
x = (4170.97 - 0.75·4600) / (0.75 - 0.73)
x = 36048.5