Write the equation of the line that has a slope of 2/3 and a y intercept of -8

What can you determine about the solutions of this system

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.

X+ y = 5 ; x - y =3 solve using linear combination