There is a math problem about washing dishes in Confucius Arithmetic Classic, an ancient math book in China: A peasant woman is washing dishes by the well, and her neighbor asks, "How many guests are there in your house?"
Because there is a soup bowl for every three people and a dish bowl for every two people, the number of guests must be a multiple of 6.
With 6 people as the unit, a * * * will use 2 soups, 3 dishes and 6 meals 1 1 bowl.
55/ 1 1=5, that is, there are five such units, each with six people.
So * * * has 30 guests.