80% of n is 32 what is the value of n​

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.

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

The square root of 9x plus 7 plus the square rot of 2x equall to 7