\[| - 0,42| = |x| \cdot | - 2,8|\]
\[|x| = | - 0,42|\ :| - 2,8|\]
\[|x| = 42\ :280\]
\[|x| = \frac{42}{280} = \frac{3}{20} = \frac{15}{100} = 0,15\]
\[x = \pm 0,15.\]
\[Ответ:x = \pm 0,15.\]