Answer:
Yes, they can install chairs in less than one day
Step-by-step explanation:
1- For company X:
They can install the chairs in 10 hours
This means that:
in 1 hour, company X would have finished 1/10 of the work required
2- For company Y:
They can install the chairs in 15 hours
This means that:
in 1 hour, company Y would have finished 1/15 of the work required
Now, we will calculated the fraction of work that will be finished in one hour if the two companies worked together:
fraction of work = fraction finished by X + fraction finished by Y
fraction of work = 1/10 + 1/15
fraction of work = 1/6
This means that:
In one hour, 1/6 of the work would be finished
which means that the two companies would need 6 hours to finish the entire work
It's obvious that 6 hours is less than one day.
Therefore, the answer is YES.
Hope this helps :)