б) \(\frac{1}{2} : 13 = \frac{1}{2}x : 4 \frac{1}{3}\). \( \frac{1}{2} : 13 = \frac{x}{2} : \frac{13}{3} \) \( \frac{1}{26} = \frac{x}{2} \cdot \frac{3}{13} \) \( \frac{1}{26} = \frac{3x}{26} \) \( 1 = 3x \) \(x = \frac{1}{3}\). Ответ: \(x = \frac{1}{3}\)