Решите пример 1)15/4:(18/7-13/12)=?

$\frac{15}{4} *( \frac{18}{7} - \frac{13}{12} )= \frac{15*18}{4*7} - \frac{15*13}{4*12}= \frac{15*9}{2*7} - \frac{5*13}{4*4}= \frac{135}{14} - \frac{65}{16} = \frac{8*135-7*65}{112} =$
$\frac{8*135-7*65}{112} = \frac{5(27*8-13*7)}{112} = \frac{5(216-91)}{112} =\frac{5*125}{112}= \frac{625}{112}$

деление
$\frac{15}{4} /( \frac{18}{7} - \frac{13}{12} )= \frac{15}{4} /( \frac{18*12-13*7}{7*12} )= \frac{15}{4} /( \frac{216-91}{7*12} )= \frac{15}{4} /( \frac{125}{7*12} )= \\ = \frac{15*7*12}{4*125} =\frac{3*7*3}{25}=\frac{63}{25}$