[tex]\begin{gathered} v_{light}=300,000\text{ }km\text{ /s}=3x10^{5^{}}\text{ }km\text{ /s} \\ t=12.5\text{ years} \\ \text{1 year has }31,536,000s=3.1536x10^7\text{ s} \\ v=\frac{x}{t} \\ \text{Solving x} \\ x=vt \\ x=(3x10^{5^{}}\text{ }km\text{ /s})(3.1536x10^7\text{ s}) \\ x=9.4608x10^{12^{}}km \\ \text{The star is }9.4608x10^{12^{}}km\text{ far from the earth} \end{gathered}[/tex]
