4/5+×=13/5 how do i solve this problem

Acircle has a circumference of 28.36 units what is the diameter of the circle

What term makes it inconsistent y=2x - 4

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.