Question

Срочнооо помогите упростить
Алгебра 7класс
2,4,7,8

Answer 1

$2)\; \; 1\frac{1}{9}\cdot (1,8x-2\frac{1}{4}y)-7,2\cdot (1\frac{1}{8}x+1\frac{7}{12}y)=\\\\=\frac{10}{9}\cdpt (\frac{18}{10}x-\frac{9}{4}y)-\frac{36}{5}\cdot (\frac{9}{8}x+\frac{19}{12}y)=2x-\frac{5}{2}y-\frac{81}{10}x-\frac{57}{5}y=\\\\=-\frac{61}{10}x-\frac{139}{10}y=-6,1x-13,9y$

$4)\; \; -2,4\cdot (\frac{1}{3}m-0,5n)-5,4\cdot (\frac{1}{9}m-1\frac{1}{6}n)=\\\\=-\frac{12}{5}\cdot (\frac{1}{3}m-\frac{1}{2}n)-\frac{27}{5}\cdot (\frac{1}{9}m-\frac{7}{6}n)=-\frac{4}{5}m+\frac{6}{5}n-\frac{3}{5}m+\frac{63}{10}n=\\\\=-\frac{7}{5}m+\frac{75}{10}n=-1,4m+7,5n$

$7)\; \; -2\frac{1}{9}-(-4\frac{2}{11}+1\frac{8}{9})=-\frac{19}{9}+\frac{46}{11}-\frac{17}{9}=\frac{-209+414-187}{99}=\frac{18}{99}=\frac{2}{11}$

$8)\; \; 1,57-(5,3-3,43)=1,57-1,87=-0,3$