If the sum of x and y is 90, and x is 12 more than three times y, what systems of equations can represent this

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.

(least common multiples) the answer that i had in the 1st step was lcm of airline tickets sold=72. idk if that even matters but just in case. ! three co-workers are busy selling airline tickets over the phone. in an 8-hour day, charles can sell 8 airline tickets, ann can sell 9 airline tickets, and michelle can sell 6 airline tickets. step 2 of 2: what is the smallest number of 8-hour days needed for each of them to achieve the same number of sales? it takes charles . it takes . it takes .

Find the area of the regular hexagon if a side is 20 cm.