1)0.8/(1-1/9)= найдите значение выражения2)5-2x=11-7(x-2) решите...

============ 1 ============

$\frac{0.8}{1- \frac{1}{9} } =\frac{0.8}{ \frac{9}{9} - \frac{1}{9} } =\frac{ \frac{8}{10} }{ \frac{8}{9} } = \frac{4}{5} \cdot \frac{9}{8}= \frac{9}{10} =0.9$

============ 2 ============

$5-2x=11-7(x-2)\\ 5-2x=11-7x+14\\ -2x+7x=25-5\\ 5x=20\\ x=4$

============ 3 ============

$\frac{a+x}{a} : \frac{ax+x^2}{a^2} =\frac{a+x}{a} \cdot \frac{a^2}{x(a+x)} = \frac{a}{x} \\\\ a=67, x=-25 \Rightarrow \frac{67}{-25}=-2.68$