La a); b) si c) merge aceeasi regula:
[tex] \frac{a}{b} + \frac{c}{d} + \frac{e}{f} = \frac{5}{9}\\
\frac{a+c+e}{b+d+f} = \frac{5}{9}, at.\\
b+d+f= \frac{9*(a+c+e)}{5}\\
a)b+d+f= \frac{9*10}{5}=18\\
b)b+d+f= \frac{9*25}{5}=45\\
c)b+d+f= \frac{9*35}{5}=63\\ [/tex]
