4. Решите уравнения: a) x - 5 3/8 = 7 1/8; б) 1/7 * x = 4 3/7; в) 7/12 : x = 2/3

a) \(x - 5 \frac{3}{8} = 7 \frac{1}{8}\) \(x = 7 \frac{1}{8} + 5 \frac{3}{8}\) \(x = 12 \frac{4}{8}\) \(x = 12 \frac{1}{2}\) б) \( \frac{1}{7} x = 4 \frac{3}{7} \) \( \frac{1}{7} x = \frac{31}{7} \) \( x = \frac{31}{7} \cdot 7 \) \( x = 31 \) в) \( \frac{7}{12} : x = \frac{2}{3} \) \( x = \frac{7}{12} : \frac{2}{3} \) \( x = \frac{7}{12} \cdot \frac{3}{2} \) \( x = \frac{7 \cdot 3}{12 \cdot 2} \) \( x = \frac{7 \cdot 3}{4 \cdot 3 \cdot 2} \) \( x = \frac{7}{8} \) Ответ: a) \(x = 12 \frac{1}{2}\) б) \(x = 31\) в) \(x = \frac{7}{8}\)