Du meinst vermutlich:
(c-d)/(c+d) - (d-c)/c^2 : (c+d)/ (cd)
Nun gilt erst mal Punkt- vor Strichrechnung. Bruchdivision.
= (c-d)/(c+d) - (d-c)/c^2 * (cd)/ (c+d)
= (c-d)/(c+d) - ((d-c) * (cd))/ ((c+d)c^2) | Brüche gleichnamig machen.
= (c^2*(c-d))/((c+d)c^2) - ((d-c) * (cd))/ ((c+d)c^2) | Brüche Subtrahieren.= (c^2*(c-d)) - ((d-c) * (cd))/ ((c+d)c^2) | c ausklammern
= ( c*(c*(c-d)) - ((d-c) * (d)))/ ((c+d)c^2) | c kürzen
= (c*(c-d)) - ((d-c) * (d))/ ((c+d)c) | Zähler vereinfachen
= (c^2 - cd - (d^2 - cd)) /((c+d)c) |
= (c^2 - cd - d^2 + cd) /((c+d)c)
= (c^2 - d^2 ) /((c+d)c) | 3. Binom
= ((c-d)(c+d))/((c+d)c) |kürzen
= (c-d) / c