Question

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

Answer 1

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

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

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

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