1. The problem statement, all variables and given/known data "A rifle is fired in a valley with parallel vertical walls. The echo from one wall is heard 2.0 s after the rifle was fired. The echo from the other wall is heard 2.0 s after the first echo. How wide is the valley? 2. Relevant equations I dont know any relevant equations. v=wavelength x frequency? Do I have to convert something into decibels? 3. The attempt at a solution time=2 s distance=? .