Can someone please help me with math.

If the wwight of a package is multiplied by 7/10 the result is 65.8 find the weight of the package

F(n + 1) = f(n) – 8. if f(1) = 100, what is f(6)?

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.