A school plans to buy a number of computers, first learned from two shopping malls that the price of the same model of computer is 4000 yuan, and there are certain discounts for buying more computers The preferential terms of a shopping mall are: the first one is charged according to the original quotation, and the other one is 25% off. The preferential terms of B shopping mall are: 20% off (1) If you buy in a mall, you need to charge (); if you buy in B mall, you need to charge () (2) Under what circumstances are the charges of the two shopping malls the same? Under what circumstances is it more favorable to buy in a shopping mall? Under what circumstances is it more favorable to buy in B shopping mall?

A school plans to buy a number of computers, first learned from two shopping malls that the price of the same model of computer is 4000 yuan, and there are certain discounts for buying more computers The preferential terms of a shopping mall are: the first one is charged according to the original quotation, and the other one is 25% off. The preferential terms of B shopping mall are: 20% off (1) If you buy in a mall, you need to charge (); if you buy in B mall, you need to charge () (2) Under what circumstances are the charges of the two shopping malls the same? Under what circumstances is it more favorable to buy in a shopping mall? Under what circumstances is it more favorable to buy in B shopping mall?

Purchase x computers
The cost of shopping mall a is 4000 + 4000 x (1-25%) x (x-1)
It costs 4000 x (1-20%) x x in shopping mall B
If the left and right offshore sides are equal, x = 5 can be obtained
When x > 5, it is more favorable in a, when x > 5, it is more favorable in a