Dish 1*** 4 kinds

Staple food 1*** 3 kinds

Choose 2 kinds of dishes, 1*** has 4×3÷2 =6 selection methods

Choose 1 staple food, and there are 3 selection methods

The total selection methods are: 6×3=18 types

p>

124÷18=6 more than 16

Think of the 18 choices in a *** as 18 drawers

Put 124 people into 18 drawers. There must be more than 7 people in at least 1 drawer

So at least 7 students bought the same vegetables and staple food