Решите уравнения. a-0,2a = 4/5; 2) 0,78: (6,7-x) = 2,6 3) 2,5x + x = 0,7 4) 1,7*(3,4a-1,4a) = 51

Давай решим уравнения по порядку! 1) a - 0.2a = \frac{4}{5} \(0.8a = \frac{4}{5}\) \(0.8a = 0.8\) \(a = \frac{0.8}{0.8}\) \(a = 1\) 2) 0.78 : (6.7 - x) = 2.6 \(6.7 - x = \frac{0.78}{2.6}\) \(6.7 - x = 0.3\) \(x = 6.7 - 0.3\) \(x = 6.4\) 3) 2.5x + x = 0.7 \(3.5x = 0.7\) \(x = \frac{0.7}{3.5}\) \(x = 0.2\) 4) 1.7 \cdot (3.4a - 1.4a) = 51 \(1.7 \cdot (2a) = 51\) \(3.4a = 51\) \(a = \frac{51}{3.4}\) \(a = 15\)

Ответ: 1) a = 1; 2) x = 6.4; 3) x = 0.2; 4) a = 15