Answer:
80 rooms
Explanation:
Given: 70 of the rooms in a hotel are full such that the hotel is 87.5% full.
To find: total number of rooms in the hotel
Solution:
Number of filled rooms 

Percentage if filled rooms 

Let 
 denotes total number of rooms.
 denotes total number of rooms.
Therefore,

So, there are 
 rooms in the hotel.
 rooms in the hotel.