Answer:
10 students
Step-by-step explanation:
I've drawn a venn diagram to explain the distribution in this question and attached it.
From the venn diagram, we can see that;
(M) = 60
(S) = 50
(M ∩ S) = 20
Now, to find how many of them failed both subjects, we will use the formula;
100 = (M' ∩ S') + (M) + (S) - (M ∩ S)
Where (M' ∩ S') is number of people that failed both subjects
Plugging in the relevant values we have;
100 = (M' ∩ S') + 60 + 50 - 20
100 = (M' ∩ S') + 90
(M' ∩ S') = 100 - 90
(M' ∩ S') = 10
