The original unit price of the same kind of review materials was 65 yuan, and then the bookstore launched a price reduction promotion. The Sunshine Bookstore sells at "25% off" the original price; the student bookstore offers "buy four get one free". Mr. Wang wants to buy five of these materials as prizes for the students. Which bookstore should he choose to buy from? How much cheaper is it?
同一种复习资料原来的单价是65元，后来书店开展降价促销活动．阳光书店按原价的"七五折"出售；学生书店则是"买四送一"，王老师要买5本这种资料作为奖品送给学生，他应该选择去哪家书店买比较便宜？便宜多少元钱？
<gadget id="calculator">65 * 4</gadget>
<output>260</output>

<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">65 * (3/4) * 5</gadget>
<output>975/4 = around 243.75</output>

<gadget id="calculator">260 - (975/4)</gadget>
<output>65/4 = around 16.25</output>

<result>65/4 = around 16.25</result>