Okey dokey this is really simple actually. The way to do problems like this is to first write out the equation as if there were an equal sign. (x=18000 or x=4). Then all you have to do is figure out which way to put the greater than / less than sign. To do that the open end should be facing the greater number. (Like an alligators mouth. He wants more food so he eats whatever number is bigger (and yes alligators eat numbers.. don't question my sanity :l ).
So for number 11 you know that MORE than 18000 tickets were sold (whoa thats a lot of tickets). This means that the number of tickets sold (x) is GREATER than 18000. Therefore, x>18000.
Do the same thing for number 12. The number of students absent was LESS than 4. This means that 4 is bigger than the number of students absent. So, x<4.