At a particular school with 43 students, each student takes chemistry, biology, or both. The chemistry class is three times as large as the biology class, and 5 students are taking both classes. How many people are in the chemistry class?
Total = 43
C = 3B
5 taking both
43 = 3B + B - 5 add 5 to both sides and simplify
48 = 4B divide both sides by 4
12 = Biology
36= Chemistry
Here's the Venn Diagram :
+1310 
