Nur zusammenfassen
[200, 0, 50] + r·[10, 20, 0] - ([230, 150, 30] + r·[12, 15, 2])
= [200, 0, 50] + r·[10, 20, 0] - [230, 150, 30] - r·[12, 15, 2]
= [200, 0, 50] - [230, 150, 30] + r·[10, 20, 0] - r·[12, 15, 2]
= [-30, -150, 20] + r·[-2, 5, -2]
= [-30 - 2·r, -150 + 5·r, 20 - 2·r]