Why is this urgent?
I edited your post to make it coherent..Please review the posting guidelines here: rules-for-posting-please-read-this-before-posting-133935.html
Anyway, here is the solution:
Total = Chemistry + Biology - Both + Neither
200 = 130 + 150 - Both + N
We know that N (Neither) must be at least 30, so set N=30 and solve:
200 = 130 + 150 - Both + 30
200 = 310 - Both
Both = 110
Even if you're not sure whether 110 is the highest or lowest Both could possibly be, it doesn't matter, because you know it's a boundary point of the range, which means only answers D or E could be correct.
Both can not be greater than 130, because even if every chemistry major was also a biology major, there are only 130 chemistry majors total. D the solution.
My Applicant Blog: http://hamm0.wordpress.com/