How do i solve order of operations

Find and simplify an expression for the area of five rows of x squares with side lengths of x centimeters.

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.

2,10,-50 next two numbers geometric sequence