Answer:
10 student failed in both subjects.
Explanation:
Since out of 100 students who appeared in grade VIII annual examination of Ram Janaki Secondary School, 60 passed in mathematics, 50 in science and 20 students passed in both subjects, to determine how many failed in both subjects the following calculation must be performed:
(100 - 20) - (60 - 20) - (50 - 20) = X
80 - 40 - 30 = X
40 - 30 = X
10 = X
Therefore, 10 student failed in both subjects.