Решите уравнения: 3) \((5x+8)-(8x+14)=9\); 4) \(2.7+3y=9(y-2.1)\); 5) \(0.3(8-3y)=3.2-0.8(y-7)\); 6) \(\dfrac{5}{6}\left(\dfrac{1}{3}x-\dfrac{1}{5}\right)=3x+3\frac{1}{3}\).

1. \((5x+8)-(8x+14)=9\).

   \(5x+8-8x-14=9\), откуда \(-3x-6=9\), \(-3x=15\), \(x=-5\).

2. \(2.7+3y=9(y-2.1)\).

   \(2.7+3y=9y-18.9\), поэтому \(21.6=6y\), \(y=3.6\).

3. \(0.3(8-3y)=3.2-0.8(y-7)\).

   \(2.4-0.9y=3.2-0.8y+5.6=8.8-0.8y\).

   \(-0.1y=6.4\), поэтому \(y=-64\).

4. \(\dfrac{5}{6}\left(\dfrac{x}{3}-\dfrac{1}{5}\right)=3x+3\frac{1}{3}\).

   \(\dfrac{5x}{18}-\dfrac{1}{6}=3x+\dfrac{10}{3}\).

   Умножим на 18: \(5x-3=54x+60\), значит \(-55x=63\), \(x=-\dfrac{63}{55}\).

Ответ: 3) \(x=-5\); 4) \(y=3.6\); 5) \(y=-64\); 6) \(x=-\dfrac{63}{55}\).