Question

A group of 1000 patients each diagnosed with a certain disease is being analyzed with regard to the disease symptoms present. The symptoms are labeled A,B,and C, and each patient has at least one symptom. Also,
900 have either symptom A or B (or both)
900 have either symptom A or C (or both)
800 have either symptom B or C (or both)
650 have symptom A
500 have symptom B
550 have symptom C

Determine:
1. The number who had both symptoms A and B
2. The number who had either symptom A or B (or both) but not C
3. The number who had all three symptoms


I cant seem to figure this out..

Answer 1

1. (just A + just B)-(900 have either symptom A or B (or both)= 250

Answer 2

what does your number 2 mean?