I need an equation for B and explanation for C click on the pic to show the info you need

first to answer with a good explanation gets brainliest ​

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)

What is the value of x in the following equation. -x ^3/2 = -27

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.