Class 6 (2) is going to have a spring outing. The price of a brand of milk is 2 yuan per bottle. If you buy it in department store a, you can get one free if you buy 5 bottles; if you buy it in department store B, you can get 10% discount. There are 42 students in the class. If you want to prepare a bottle of milk for each student, which department store should you go to? Why? Do not write in the form of a column,

Class 6 (2) is going to have a spring outing. The price of a brand of milk is 2 yuan per bottle. If you buy it in department store a, you can get one free if you buy 5 bottles; if you buy it in department store B, you can get 10% discount. There are 42 students in the class. If you want to prepare a bottle of milk for each student, which department store should you go to? Why? Do not write in the form of a column,

A: buy 37 bottles, give 5 bottles free, 37 * 2 = 74 yuan
B: buy 42 bottles, 42 * 2 * 0.9 = 75.6 yuan
Therefore, it is necessary to select a shopping mall

Class 6 (2) is going on a spring outing. Each bottle of milk of a certain brand costs 2 yuan. If you buy it in a shopping mall, you can get one free if you buy 5 bottles; if you buy it in B shopping mall, you can get 10% discount

The problem is not complete --