What Influence Has Music Caused to World's Cultural Events?

Amplitude is: a. the number of waves in a certain amount of time. b. the distance between the top or bottom of a wave and the center of the wave. c. the noise floor acceptable in recording. d. the distance between two identical points on a wave.

For the difference command to work, what needs to happen?

4/5 of a number is 64 find the number