What fraction of all students took biology and took chemistry? OR

What fraction of the remaining students took biology and took chemistry?

For the former correct answer will be

5/6 [(1/2+1/3)/(1)] and for the later correct answer will be

7/9[(1/2*2/3+1/3*3/4)/(1/3+1/4+1/6)].

It took me 7 minutes to understand that too after matching the answers that what exactly the question is ??

Chembeti wrote:

Every student of a certain school must take one and only one elective course. In last year, 1/2 of the students took biology as an elective, 1/3 of the students took chemistry as an elective, and all of the other students took physics. In this year, 1/3 of the students who took biology and 1/4 of the students who took chemistry left school, other students did not leave, and no fresh student come in. What fraction of all students took biology and took chemistry?

A. 7/9

B. 6/7

C. 5/7

D. 4/9

E. 2/5

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