Mick paid $2.94 in sales tax of an item that cost $42.00 before tax. at that rate, how much would he pay in sales tax for an item that costs $58.00 before tax?

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.