kind of football, the price of three stores A, B, and C is 25 yuan each, and the school needs to buy 60. The promotion methods of the three stores are as follows: Store A will buy 10 and get 2 free, and store B will not give away less than 10. You can get a 15% discount; store C will return 20 yuan for every 100 yuan of shopping. Which store is more cost-effective for the school to buy? How much is the minimum required?
一种足球，甲、乙、丙三家商店的价格都是每个25元，学校要买60个，三个商店促销方式如下：甲商店是买10个送2个，不足10个不送；乙商店可以打八五折；丙商店是购物每满100元，返还20元．学校到哪家商店购买比较合算？最少需要多少元？
<gadget id="calculator">25 * 60</gadget>
<output>1_500</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">60 * (1/4)</gadget>
<output>15</output>

<gadget id="calculator">15 * 20</gadget>
<output>300</output>

<gadget id="calculator">1_500 - 300</gadget>
<output>1_200</output>

<result>1_200</result>