Please help I really need it I don't understand

What is the measure of ac? 5 units 13 units 26 units 39 units

(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 .

Which describes the difference between the graph of f(x)=x^2 and g(x)=-(x^2-2)