An organic compound undergoes first-order decomposition. The time taken for its decomposition to $1 / 8$ and $1 /$ 10 of its initial concentration are $t_{1 / 8}$ and $t_{1 / 10}$ respectively. What is hte value of $\frac{\left[1_{t / 8}\right]}{\left[t_{1 / 10}\right]} \times 10 ?\left(\log _{10} 2=0.3\right)$