A roll of nickels have 40 nickels in them. How many nickels are needed to fill 8 coin rolls .. i need help asap

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.

How many different three-digit numbers can be formed using the digits 1 comma 2 comma 9 comma 6 comma 4 comma 3 comma and 8 without repetition? for example, 664 is not allowed.

Look at triangle wxy what is the length (in centimeters) of the side wy of the triangle?