The exponential function y=3(4)^x grows by a factor of 4 between x=1 and x=2

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.

In a column proof the right column states your reasons

I’m still confused on how to work the percentages