Answer:
4 more people
Explanation:
6 people can paint several offices in 5 days
1 people can do same work in = 6 × 5 = 30 days
To complete the same job in 3 days people need =

= 10 people
Need to hire people = 10 - 6 = 4 people
4 more people need to be hired to complete the same job in 3 days.