<Tr> <Td> − 25 </Td> <Td> 315.77 </Td> <Td> 1.4224 </Td> <Td> 449.1 </Td> </Tr> <P> Given normal atmospheric conditions, the temperature, and thus speed of sound, varies with altitude: </P> <Table> <Tr> <Td> Altitude </Td> <Td> Temperature </Td> <Td> m / s </Td> <Td> km / h </Td> <Td> mph </Td> <Td> kn </Td> </Tr> <Tr> <Td> Sea level </Td> <Td> 15 ° C (59 ° F) </Td> <Td> 340 </Td> <Td> 1,225 </Td> <Td> 761 </Td> <Td> 661 </Td> </Tr> <Tr> <Td> 11,000 m − 20,000 m (Cruising altitude of commercial jets, and first supersonic flight) </Td> <Td> − 57 ° C (− 70 ° F) </Td> <Td> 295 </Td> <Td> 1,062 </Td> <Td> 660 </Td> <Td> 573 </Td> </Tr> <Tr> <Td> 29,000 m (Flight of X-43A) </Td> <Td> − 48 ° C (− 53 ° F) </Td> <Td> 301 </Td> <Td> 1,083 </Td> <Td> 673 </Td> <Td> 585 </Td> </Tr> </Table> <Tr> <Td> Altitude </Td> <Td> Temperature </Td> <Td> m / s </Td> <Td> km / h </Td> <Td> mph </Td> <Td> kn </Td> </Tr>

What's the speed of sound at sea level
find me the text answering this question