Let

Total number of People n(P) = 1000

People who speak Hindi n(H) = 750

People who speak Bengali n(B) = 400

We have P = n(H∪B)

⇒ n(P) = n(H)+n(B)– n (H ∩B)

= 1000 = 750+400 – n (H ∩B)

⇒n (H ∩B) = 150.

∴ 150 People can speak both languages.

H = (H–B) ∪ (H ∩B) (union is disjoint)

∴ n(H) = n(H–B) +n(H ∩B)

750 = n(H–B)+150

n(H–B) = 600

∴ 600 people speak Hindi.

B = (B–H) ∪ (H ∩B) (union is disjoint)

∴ n(B) = n(B–H) +n(H ∩B)

400 = n(B–H)+150

n(B–H) = 250

∴ 250 people speak Bengali.