9514 1404 393
Answer:
300
Step-by-step explanation:
Since nobody failed, the number who passed one or the other was 100%.
P(O + W) = P(O) +P(W) -P(O&W)
100% = 80% +70% -P(O&W)
P(O&W) = 50% = 150 students
If 150 students are 50% of the examinees, then 100% will be 300 students.
