How many people ( from the group surveyed ) read both Indian Express and Times of India?
I. Out of total of 200 readers, 100 read Indian Express, 120 read Times of India and 50 read Hindu.
II. Out of a total of 200 readers, 100 read Indian Express, 120 reads Times of India and 50 read neither.

Considering first statement only, given information will not suffice to answer that how many people read both Indian express and Times of India as data regarding intersection of all and data regarding number of people reading other 2 newspapers is not given
Now if we consider only second statement then we can answer about people reading both Indian express and Times of India as follows:
Total readers = 200 = 100 (indian express) + 120 (Times of india)  + 50 (Reading none) - Reading both.
So Reading both newspapers = 270-200 = 70