Center Of Mass

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