Well, in AP Physics class we are using Giancoli 6th edition book. It doesn't have equations for Damped simple harmonic oscillator. I looked at the following link: http://farside.ph.utexas.edu/teaching/336k/lectures/node19.html but I do not know how to get started.
The given are Amplitude = .05 m, Time = 3.5 sec, Mass = .58kgs, k = 150 N/m and we nee to find Friction force.