[tex]x = \frac{a}{c-d} \ \ /\cdot(c-d)\\\\x(c-d) = a\\\\xc - xd = a\\\\xc = a+xd \ \ /:x\\\\c = \frac{a}{x} + d[/tex]
Z:
c ≠ d ∧ x ≠ 0
