Explicație pas cu pas:
[tex]\left[\frac{1}{2} \times \left( - \frac{3}{5} \right) \right] + \left[ - \frac{1}{5} \times \left(\frac{3}{7} \right) \right] = \\ = \left( - \frac{3}{10} \right) + \left( - \frac{3}{35} \right) = - \frac{3}{10} - \frac{3}{35} \\ = - \frac{3 \times 7}{70} - \frac{3 \times 2}{70} = - \frac{21 + 6}{70} = - \frac{27}{70}[/tex]
