4-ое заданиеПОМОГИТЕ РЕШИТЬ!!!!!!ОТВЕТ НЕ ВЫХОДИТ.

Решите задачу:

$1) 2: \frac{16}{5} = \frac{2}{1} * \frac{5}{16} = \frac{5}{8} \\ 2)3 \frac{1}{4} - \frac{2}{3} =2 \frac{15}{12} - \frac{8}{12} =2 \frac{7}{12} \\ 3) \frac{31}{12} :3= \frac{31}{36}\\ 4)2 \frac{5}{18} - \frac{17}{36} =1 \frac{46}{36} - \frac{17}{36} =1 \frac{29}{36} \\ 5) \frac{65}{36} : \frac{65}{18} =\frac{65}{36} *\frac{18}{65} = \frac{1}{2} \\ 6) \frac{5}{8} + \frac{31}{36} =\frac{45}{72} + \frac{62}{72} = \frac{107}{72} \\$
$7) \frac{107}{72} -\frac{1}{2} =\frac{107}{72} -\frac{36}{72} = \frac{71}{72}$