Out of 120 persons, 80 are Indians and 40 are foreigners.

Out of 120 persons, 70 can speak English, and the rest cannot.

The maximum possible number of Indians who can speak English is 70, i.e. if all the English-speaking people are Indians.

The minimum possible number of Indians who can speak English is 30, i.e. if all the foreigners speak English.

So, English-speaking Indians will fall in the range of 30 to 70.