Explicação passo a passo:
[tex]{30\over10}\to simplificando~~corta ~o ~zero = \fbox{${3\over1}$}\\ \\ \\ {60\over12} \to {60:12\over12:12}=\fbox{${5\over1}$}\\ \\ \\ {20\over5} \to {20:5\over5:5}=\fbox{${4\over1}$}[/tex]
