Two masses of \( 3.4 \, \mathrm{kg} \) and \( 2.5 \, \mathrm{kg} \) are accelerated from an initial speed of \( 5 \, \mathrm{m\, /s} \) and \( 12 \, \mathrm{m\, /s} \), respectively. The distances traversed by the masses in the \( 5^{\text{th}} \) second are \( 104 \, \mathrm{m} \) and \( 129 \, \mathrm{m} \), respectively. The ratio of their momenta after \( 10 \, \mathrm{s} \) is \( \dfrac{x}{8} \). The value of \( x \) is ______.