The linear function is y = 1440x.
(Substitute 5 for x)
(Multiply: )
The sound travel 7200 meters in 5 seconds.
![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=f427cfdba526714686d6c9aae5ae4ea2.png\")
(Substitute 5 for x)![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=cb515b66afdf9fb14e78bcd9666672b8.png\")
(Multiply: ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=489829bb75b6d1b0bb82beb84763a47e.png\")
)![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")