7m-5-n-8k term I want to know what it is

Which ordered pair (c,d) is a solution to the given system of linear equations- c+2d=13 -9c-4d=-15

What is the average rate of change for this function for the interval from x=2 to x=4 ?

(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 .