Problem $5$: A student standing in a canyon yells echo, and her voice produces a sound wave of frequency of f $=0\mathrm{.}68$ kHz$.$ The echo takes t $=3\mathrm{.}9$ s to return to the student. Assume the speed of sound through the atmosphere at this location is v $=325$ m$/$s$.($a$)$ What is the wavelength of the sound wave in meters? $($b$)$ Input an expression for the distance, d$,$ the canyon wall is from the student. $($c$)$ How many wavelengths are between the student and the wall?