1. 420 : (70 * X) = 25
\[ 70 imes X = 420 : 25 \]
\[ 70 imes X = 16.8 \]
\[ X = 16.8 : 70 \]
\[ X = 0.24 \]
2. 0,25x - 0,8x - 4,35 = 2
\[ (0.25 - 0.8)x = 2 + 4.35 \]
\[ -0.55x = 6.35 \]
\[ x = 6.35 : (-0.55) \]
\[ x \approx -11.545 \]
Ответ: X = 0.24; x \approx -11.545