In rdt protocols discussed in book, why did we need to introduce sequence numbers and timers?

The most complicated four letter word

Ihave been given the number of guns per 100, and the total firearm-related deaths per 100,000. i have to find the actual number of guns per country and actual number of gun-related deaths. if somebody could show me how to do 1 question, i can finish the rest, i am just confused. tia

What shows the web address of the page that is currently displayed in the workspace? status window toolbar location bar internet box