let x be the seats in the small van and y the seats in the large van. how many seats does the large van have?
a company uses two vans to transport worker from a free parking lot to the workplace between 7:00 and 9:00a.m. one van has 6 more seats than the other. the smaller van makes two trips every morning while the larger one makes only one trip. the two vans can transport 57 people, maximum.