Să se efectueze
[tex] \frac{1}{2} + \frac{3}{4} + \frac{1}{5} [/tex]
[tex] \frac{1}{48} + \frac{7}{80} [/tex]
[tex] \frac{1}{2} + \frac{4}{5} + \frac{7}{10} [/tex]
[tex] \frac{1}{12} + \frac{5}{24} + \frac{7}{48} [/tex]