Bài 1:
1) Ta có: \(\frac{x}{5}=\frac{6}{-10}\)
\(\Leftrightarrow x=\frac{6\cdot5}{-10}=\frac{30}{-10}=-3\)
Vậy: x=-3
2) Ta có: \(\frac{3}{x}=\frac{-33}{77}\)
\(\Leftrightarrow x=\frac{3\cdot77}{-33}=-7\)
Vậy: x=-7
3) Ta có: \(\frac{x}{-10}=\frac{-4}{8}\)
\(\Leftrightarrow x=\frac{-4\cdot\left(-10\right)}{8}=\frac{40}{8}=5\)
Vậy: x=5
4) Ta có: \(\frac{-4}{8}=\frac{-7}{x}\)
hay \(x=\frac{-7\cdot8}{-4}=\frac{-56}{-4}=14\)
Vậy: x=14
5) Ta có: \(\frac{x}{-20}=\frac{9}{12}\)
hay \(x=\frac{9\cdot\left(-20\right)}{12}=\frac{-180}{12}=-15\)
Vậy: x=-15
6) Ta có: \(\frac{-24}{x}=\frac{-12}{8}\)
hay \(x=\frac{-24\cdot8}{-12}=2\cdot8=16\)
Vậy: x=16
7) Ta có: \(\frac{x}{-7}=\frac{6}{7}\)
hay \(x=\frac{6\cdot\left(-7\right)}{7}=\frac{-42}{7}=-6\)
Vậy: x=-6
8) Ta có: \(\frac{-12}{x}=\frac{18}{21}\)
hay \(x=\frac{-12\cdot21}{18}=-14\)
Vậy: x=-14
