Fraction on French and Spanish clubs

Question

In a French class, each student belongs to the French club or the Spanish club. In this class, Fbstidents are in the French club, S students are in the Spanish club, and N of these students are in both the French and the Spanish clubs. What fraction of the class belongs to the French club but not the Spanish?

Answer 1

well then there are F+S-N students altogether...

F-N of them are in the French club ONLY

S-N of them are in the Spanish club ONLY

so (F-N)/(F+s-n) are in the french club only as a fraction

and (S-n)/(F+s-n) are in the fraction of student in spanish club only

n/(F+s-n) is the fraction of the students in both...

note that [(F-n)+(S-n)+n]/(s+f-n) = (F+s-2n+n)/(s+f+n) = (f+s-n)/(f+s-n) = 1