Ellie is blocking off several rooms in a hotel for guests coming to her wedding. the hotel can reserve small rooms that can hold 3 people, and large rooms that can hold 6 people. ellie booked a total of 15 rooms which can accommodate 69 guests altogether. write a system of equations that could be used to determine the number of small rooms reserved and the number of large rooms reserved. define the variables that you use to write the system.