Find the missing variable in each of the following

The table shown below gives the approximate enrollment at the university of michigan every fifty years. how many more students were enrolled at the university of michigan in 1950 than in 1900?

Asandwich shop has 18 tables. each table seats up to 4 people. to find the greatest number of people that can be seated, you can solve p4 ≤ 18. which step is the best way to solve the inequality? plz asap i repeat plz

It would mean the world to me if somebody me with this