Match each unit rate to its ratio. PLEASE HELP

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

#1-20 state whether the angles are alternate interior, alternate exterior, vertical, or corresponding angles.

(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 .