3)

[tex]\frac{1}{6} x=\frac{7}{48} \\x = \frac{7}{48} : \frac{1}{6}\\ x=\frac{7*1}{8*1} \\x = \frac{7}{8}[/tex]

4)

[tex]\frac{3}{4} -2\frac{1}{7} : 3\frac{1}{3}\\\frac{21}{28} - 2\frac{4}{28} : \frac{10}{3} \\-(1\frac{32}{28} -\frac{21}{28} ):\frac{10}{3} \\-1\frac{11}{28} :\frac{10}{3} = -\frac{39}{28} : \frac{10}{3} \\-\frac{39*3}{28*10} = -\frac{117}{280}[/tex]

Ответ: [tex]-\frac{117}{280}[/tex].

Удачи!!!