Me! how do you factor out the coefficient of a variable? ? example: 5c - 15

Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u

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.

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?