Explicación paso a paso:
a)
[tex] \frac{3}{4} = \frac{21}{28} = \frac{15}{20} [/tex]
[tex] \frac{9}{12} = \frac{81}{108} = \frac{3}{4} [/tex]
b)
[tex] \frac{40}{25} = \frac{120}{75} = \frac{8}{5} [/tex]
c)
[tex] \frac{9}{12} = \frac{81}{108} = \frac{3}{4} [/tex]
espero que sea de tu ayuda
saludos :)
