The back wall of an auditorium is 29.0 m from the stage. If you are seated in the middle row, how much time elapses between a sound from the stage reaching your ear directly and the same sound reaching your ear after reflecting from the back wall?

4 answers

0.29 m divided by the speed of sound.

You are 14.5 m from the stage and back wall. The reflected wave from the back must make a round trip of 0.29 m before reaching you.
what is the speed of the sound
About 340 m/s in air at room temperature. If you are studying acoustics, you should know it by now.

The subject is physics, not physic. Physic has another meaning.
i am not learning acoustics...but physics..sorry for the mis-spelling...i am sorry but i don't understand your approach