Answer: 270 people
Explanation:
The ratio of the number of people who get their news from social media to the number of people who their news from other sources is 3 to 7.
This shows that the number of people who get their news from social media is 3 out of 10 i.e (3+7).
Therefore, the number of people in a town of 900 people that get their news from social media will be:
= 3/10 × 900
= 270 people.