The 7th grade French and Spanish classes each have 21 students in them, and there are six students in the 7th grade taking both languages. If everyone in the 7th grade is in at least one of the two language classes, how many students are taking just one of the two classes?  Select the correct option:
A) 24	B) 28	C) 30	D) 32	E) 34
French class + Spanish class = 42 students.   Six students are in both classes so they were counted twice.   The number of students taking just one class is 42 - 2(6) = 30.   The answer is 30.
<result>C</result>
The 7th grade French and Spanish classes each have 21 students in them, and there are six students in the 7th grade taking both languages. If everyone in the 7th grade is in at least one of the two language classes, how many students are taking just one of the two classes?