Assuming constant speeds, the P-wave covers a distance <em>d</em> in time <em>t</em> such that
9000 m/s = <em>d</em>/(60 <em>t</em>)
while the S-wave covers the same distance after 1 more minute so that
5000 m/s = <em>d</em>/(60(<em>t</em> + 1))
Now,
<em>d</em> = 540,000 <em>t</em>
<em>d</em> = 300,000(<em>t</em> + 1) = 300,000 <em>t</em> + 300,000
Solve for <em>t</em> in the first equation and substitute it into the second equation, then solve for <em>d</em> :
<em>t</em> = <em>d</em>/540,000
<em>d</em> = 300,000/540,000 <em>d</em> + 300,000
4/9 <em>d</em> = 300,000
<em>d</em> = 675,000
So the earthquake center is 675,000 m away from the seismic station.
