Question

приведи подобные слагаемые и запеши ответ​

Answer 1

$\displaystyle 1)2m-8,5n-14m+9n=-12m-8,5n+9n=-12m+0,5n\\\\2)-\frac{2}{5}c+\frac{1}{3}b+\frac{4}{7}c=\frac{6}{35}c+\frac{1}{3}b\\\\-\frac{2}{5}c+\frac{4}{7}c=-\frac{2c}{5}+\frac{4c}{7}= -\frac{7*2c}{7*5}+\frac{5*4c}{5*7}=-\frac{14c}{35}+\frac{20c}{35}=\frac{-14c+20c}{35}=\frac{6}{35}c$