Помогите пожалуйста решить даю 20 балов номер 51

Ответ

Проверено экспертом

Автор - ndusha

1)
$12:3 frac{3}{8} -1 frac{1}{4} : frac{15}{32} =12:frac{26}{8} -frac{5}{4} : frac{15}{32} =12*frac{8}{26} -frac{5}{4}*frac{32}{15} = \ =6*frac{8}{13} -frac{1}{4}*frac{32}{3} =frac{48}{13} -frac{1}{1}*frac{8}{3} =3 frac{9}{13} -2frac{2}{3} =3 frac{27}{39} -2frac{6}{39} =1 frac{21}{39}$

2)
$1 frac{31}{35}:(2- frac{8}{9}:1 frac{19}{45} ) =frac{66}{35}:(2- frac{8}{9}:frac{64}{45} ) =frac{66}{35}:(2- frac{8}{9}*frac{45}{64} ) = \ =frac{66}{35}:(2- frac{1}{1}*frac{5}{8} ) = frac{66}{35}:(2- frac{5}{8} ) = frac{66}{35}:frac{3}{8} = 66/35*8/3=22/35*8= \ =176/35=5 frac{1}{35}$

3)
$(1 frac{1}{35}: frac{4}{5}-1 frac{8}{35} )*3 frac{1}{3} =(frac{36}{35}*frac{5}{4}-1 frac{8}{35} )*frac{10}{3} =(frac{9}{35}*frac{5}{1}-1 frac{8}{35} )*frac{10}{3} = \ =(frac{45}{35}-1 frac{8}{35} )*frac{10}{3} = (1frac{10}{35}-1 frac{8}{35} )*frac{10}{3} = frac{2}{35}*frac{10}{3} = frac{2}{7}*frac{2}{3} =4/21$

4)
$(7-1 frac{5}{9}: frac{7}{24} ): frac{20}{27} =(7-frac{14}{9}: frac{7}{24} )* frac{27}{20} =(7-frac{14}{9}* frac{24}{7} )* frac{27}{20} = \ =(7-frac{2}{3}* frac{8}{1} )* frac{27}{20} =(7-frac{16}{3})* frac{27}{20} =(7-5frac{1}{3})* frac{27}{20} =1frac{2}{3}* frac{27}{20} = \ =frac{5}{3}* frac{27}{20} =frac{1}{1}* frac{9}{4} =9/4=2 frac{1}{4}=2.25$