Answer:
3.6 hours
Explanation:
Blake can do work in hours = 9
Blake can do a part of work in 1 hour =

Ned can paint the same room in six hours.
Ned can do a part of work in 1 hour =

They can do a part of work together in 1 hour =

=
Now they can do
part of work in hour = 1
So, they can do whole work in hours =

=

Hence it will take 3.6 hours to paint the room if they work together.