Решите уравнения: 1) (14 − 21x) = 56; 2) 7(x + 7) = 10x; 3) 3(x + 8) = −3x; 4) (45 − y) + 8 = 78; 5) 5x − 5y = −8x + 1.

1. \(14-21x=56\)

   \(-21x=56-14\)

   \(-21x=42\)

   \(x=-2\)

2. \(7(x+7)=10x\)

   \(7x+49=10x\)

   \(49=3x\)

   \(x=\frac{49}{3}\)

3. \(3(x+8)=-3x\)

   \(3x+24=-3x\)

   \(6x=-24\)

   \(x=-4\)

4. \((45-y)+8=78\)

   \(53-y=78\)

   \(-y=25\)

   \(y=-25\)

5. \(5x-5y=-8x+1\)

   \(13x-5y=1\)

   \(-5y=1-13x\)

   \(y=\frac{13x-1}{5}\)

Ответ: 1) \(x=-2\); 2) \(x=\frac{49}{3}\); 3) \(x=-4\); 4) \(y=-25\); 5) \(y=\frac{13x-1}{5}\).