Уравнение вида |a| = |b| равносильно двум уравнениям: a = b или a = -b.
Случай 1: x - 0.42 = 3.4x
\[ x - 3.4x = 0.42 \]
\[ -2.4x = 0.42 \]
\[ x = \frac{0.42}{-2.4} = -0.175 \]
Случай 2: x - 0.42 = -(3.4x)
\[ x - 0.42 = -3.4x \]
\[ x + 3.4x = 0.42 \]
\[ 4.4x = 0.42 \]
\[ x = \frac{0.42}{4.4} = \frac{42}{440} = \frac{21}{220} \]
Ответ: -0.175; 21/220