Решение:
а) $\frac{-1}{3}$ = $\frac{x}{3}$
−1 = x
x = −1;
б) $\frac{-4}{5}$ = $\frac{x}{20}$
$\frac{-4 * 4}{5 * 4}$ = $\frac{x}{20}$
$\frac{-16}{20}$ = $\frac{x}{20}$
−16 = x
x = −16;
в) −$\frac{2}{3}$ = $\frac{x}{9}$
−$\frac{2 * 3}{3 * 3}$ = $\frac{x}{9}$
−$\frac{6}{9}$ = $\frac{x}{9}$;
−6 = x
x = −6;
г) −$\frac{5}{6}$ = $\frac{x}{30}$
−$\frac{5 * 5}{6 * 5}$ = $\frac{x}{30}$
−$\frac{25}{30}$ = $\frac{x}{30}$
−25 = x
x = −25;
д) −$\frac{4}{5}$ = $\frac{-20}{x}$
−$\frac{4 * 5}{5 * 5}$ = $\frac{-20}{x}$
−$\frac{20}{25}$ = $\frac{-20}{x}$
− 25 = −x
x = 25;
е) −$\frac{x}{3}$ = $\frac{-12}{18}$
−$\frac{x}{3}$ = $\frac{-12 : 6}{18 : 6}$
−$\frac{x}{3}$ = $\frac{-2}{3}$
−x = −2
x = 2.
Ответ:
а) −1;
б) −16;
в) −6;
г) −25;
д) 25;
е) 2.