How to determine the molecular formula of a compound given its molecular mass and mass percentage contribution of the involved elements?
The percentages are based on the molar mass. You have to multiply the percentages with the molar mass and divide by the mass of the atoms.

\begin{align}
\ce{C}:&amp;&amp; \frac{0.5999 \cdot 160.178}{12.011} &amp;\approx 8\\
\ce{H}:&amp;&amp; \frac{0.0503 \cdot 160.178}{1.01} &amp;\approx 8\\
\ce{N}:&amp;&amp; \frac{0.3498 \cdot 160.178}{14.007} &amp;\approx 4\\
       &amp;&amp; \implies \ce{C8H8N4}\\
\end{align}