My guy I have no idea so I would just cheat sorry
Explaination
So a general harmonic equation is Asin(2πt/T). Little t is just a variable. 6 inches is the height of one maximum and one minimum from equilibrium, so that is the amplitude A. T is the period, or the time of one cycle (or wavelength), which is 2 seconds.
The equation is therefore (in terms of seconds and inches), 6*sin(2πt/2), or 6*sin(πt).
A = 21/2 i will write something too just to fill up the space
The answer would be $35.70. 70% off would be $83.30 off of $119.
