Please show ALL the steps and the equation used in each situation.

3. Standing Waves A guitar string is clamped at both ends and is under a certain tension as it lies horizontally (along the x axis, say). When plucked, the vibrating string is found to have a harmonic at a frequency of 5600 Hz. When plucked another way, the vibrating string is observed to have a harmonic at a frequency of 8400 Hz. You are told these harmonics are consecutive modes of oscillation. The velocity of the travelling waves is 200 m/s. a) Determine the length of the string. b) If the length of the string were quadrupled and also the tension of the string were quadrupled, how would the frequency (for any harmonic) change