Atelephone surveyor earns a fixed amount for each call that she makes, as shown in the graph below. if the telephone surveyor makes 13 calls, how much will she earn total? really need

Which of the expressions (on the photo document i inserted) together represent all solutions to the following equation? 8cos(12x)+4=-4 *the answer should be in degrees.* > i would like for someone to explain the process to find the solutions for this.