[tex] \frac{1}{3} = \frac{4}{12} [/tex] | ×4
[tex] \frac{1}{4} = \frac{3}{12} [/tex] | ×3
[tex] \frac{2}{7} = \frac{8}{28} [/tex] | ×4
[tex] \frac{4}{9} = \frac{20}{45} [/tex] | ×5
