[tex] \frac{4}{5} = \frac{4 \times 3}{5 \times 3} = \frac{12}{15} [/tex]
[tex] \frac{5}{6} = \frac{5 \times 6}{6 \times 6} = \frac{30}{36} [/tex]
[tex] \frac{1}{2} = \frac{1 \times 7}{2 \times 7} = \frac{7}{14} [/tex]
[tex] \frac{3}{5} = \frac{3 \times 4}{5 \times 4} = \frac{12}{20} [/tex]
Voilà ^^
