Given a Venn diagram containing three circles representing three sets, say A, B and C. The number representing the set A or B or C is given by the addition of all the elements inside the three circles excluding the element outside the three circles.
Thus from the given Ven diagram n(P or B or C) = 10 + 2 + 8 + 4 + 6 + 5 + 7 = 42.
The total number of elements in the Venn diagram (i.e. the universal set) = 42 + 8 = 50.
P(A or B or C) = n(A or B or C) / n(Universal set) = 42 / 50 = 21 / 25
