Question

решите, пожалуйста (20б)

Answer 1

$frac{0.1}{y + 7} = frac{0.9}{y - 6} \ 0.1(y - 6) = 0.9(y + 7) \ 0.1y - 0.6 = 0.9y + 6.3 \ 0.1y - 0.9y = 6.3 + 0.6 \ - 0.8y = 6.9 \ y = 6.9 div ( - 0.8) = frac{69}{10} div ( - frac{8}{10} ) = frac{69}{10} times ( - frac{10}{8} ) = - frac{69}{8} = - 8 frac{5}{8}$