You might want to retry asking the question. It is unclear, and seems incomplete.

However, when you're dealing with 3 sets, the following formulae might come in handy. 

n (A U B U C) = n(A) + n(B) + n(C) - n(A ∩ B) - n(A ∩ C) - n(B ∩ C) + n(A ∩ B ∩ C)

n(U) = n (A U B U C) + n (A U B U C)^c

where, A, B and C are three non-empty sets, 
U denotes the Universal Set

and c (in superscript) indicates complement of a set (Complement of a set: is the difference of a set from the Universal set)

Let N and B denote the set of people whi can speak Newari and Bhojpuri reapectively.

Now, n(U)=200, n(N)=150, n(B)=80 and (A∩ B)' = 30 

i) Let (A∩ B) = x

Representing above information in a venn diagram.

From the venn diagram,

150-x + x +80-x + 30=200

Or,  260-x = 200

Or, x= 260-200

Therefore, x=60.

ii) n(N∪B) = n(N)+ n(B) - n(N∩B)

                   = 150 + 80 - 60

                   = 170

iii) n०(N)+ n०(B)= 150-x + 80-x

                             = 150-60+80-60

                             = 110

Therefore,

No.of people speaking both language=60

No.of people speaking at least one language= 170

No.of people speaking only one language= 110