I
\frac{4}{9}=\frac{1}{3}+\frac{1}{x}
\frac{4}{9}=\frac{3}{9}+\frac{1}{9}
\frac{4}{9}=\frac{1}{3}+\frac{1}{9}
II
\frac{7}{10}=\frac{1}{2}+\frac{1}{6}+\frac{1}{x}
\frac{21}{30}=\frac{15}{30}+\frac{5}{30}+\frac{1}{30}
\frac{7}{10}=\frac{1}{2}+\frac{1}{6}+\frac{1}{30}
IV
\frac{19}{20}=\frac{1}{4}+\frac{1}{5}+\frac{1}{2}
wspólny mianownik 20