\[ 3 \frac{3}{14} = \frac{3 \cdot 14 + 3}{14} = \frac{42 + 3}{14} = \frac{45}{14} \]
\[ -1 \frac{4}{21} = -\frac{1 \cdot 21 + 4}{21} = -\frac{21 + 4}{21} = -\frac{25}{21} \]
\[ y + \frac{45}{14} = -\frac{25}{21} \]
\[ y = -\frac{25}{21} - \frac{45}{14} \]
\[ y = -\frac{25 \cdot 2}{21 \cdot 2} - \frac{45 \cdot 3}{14 \cdot 3} \]
\[ y = -\frac{50}{42} - \frac{135}{42} \]
\[ y = -\frac{50 + 135}{42} = -\frac{185}{42} \]
\[ y = -4 \frac{17}{42} \]
Ответ: y = -4 17/42