Answer:


's' represent number of small rooms and 'l' represent number of large rooms.
7 small rooms and 8 large rooms were reserved.
Explanation:
Let the variable 's' represent number of small rooms and 'l' represent number of large rooms.
Given:
Holding capacity of 1 small room = 3 people
Holding capacity of 1 large room = 6 people
Total number of rooms booked = 15
Total number of guests = 69
Using unitary method to get the number of people in 's' small and 'l' large rooms.
∵ 1 small room = 3 people
∴ 's' small rooms =
people
∵ 1 large room = 6 people
∴ 'l' large rooms =
people
Now, as per question,
Total rooms = 15
⇒
------------------- (1)
Total number of persons = 69
⇒
------------------- (2)
Therefore, the system of equations that could be used to determine the number of small rooms reserved and the number of large rooms reserved are:


Now, in order to find 's' and 'l', we rewrite equation (1) in terms of 's'. This gives,

Now, plug in the value of 's' in equation (2). This gives,

Therefore, 7 small rooms and 8 large rooms were reserved.