In this equation, we are solving for f. The first thing we have to do is get rid of the denominator, so we have to multiply both sides by 9, which leaves us with 9C=5*(f-32). Then we divide both sides by 5, which is 9/5C=f-32. The last thing we have to do is add 32 to both sides to isolate f, which gives us our final equation of (5/9)C+32=f.
4 tables = 1 group. So in 10 groups of tables, there are 40 tables. Each table seats 8 students, so you multiply 8 by 40, and that leaves your answer as 320 students. :)