Explicație pas cu pas:
[tex]6 \times ( \frac{2}{12} + \frac{1}{13} + \frac{12}{13} ) = [/tex]
[tex]6 \times ( \frac{1}{6} + \frac{13}{13} ) = [/tex]
[tex]6 \times ( \frac{1}{6} + 1) = [/tex]
[tex]6 \times \frac{1 + 6}{6} = [/tex]
[tex]6 \times \frac{7}{6} = 7[/tex]