Помогите плиз решить по действиям только 3 пример

Решите задачу:

$3) 2 \frac{1}{2} * 48 = 3 \frac{2}{3} : \frac{1}{18} + 5 \frac{5}{12} : \frac{7}{36} = 81 \frac{6}{7}$

$48=\frac{48}{1}$

$2 \frac{1}{2} * \frac{48}{1} = \frac{5}{2} * \frac{48}{1} = \frac{5*48}{2*1}= \frac{240}{2}=120$

$3 \frac{2}{3}: \frac{1}{18}=\frac{11}{3} : \frac{1}{18}= \frac{11}{3}*\frac{18}{1} = \frac{11*18}{3*1}=\frac{198}{3} = 66$

$5 \frac{5}{12}:\frac{7}{36}= \frac{65}{12}: \frac{7}{36}= \frac{65}{12} * \frac{36}{7}= \frac{65*36}{12*7}= \frac{2340}{84} = \frac{2340:12}{84:12} = \frac{195}{7} = 27 \frac{6}{7}$

$120-66=54$

$54=\frac{54}{1}$

$\frac{54}{1}+ 27 \frac{6}{7} = \frac{54}{1}+ \frac{195}{7}=\frac{378}{7} + \frac{195}{7}= \frac{378+195}{7}= \frac{573}{7} = 81 \frac{6}{7}$