The school library purchased 30 copies of "Grimm's Fairy Tales" for 297 yuan. Due to the shortage of supply, the principal decided to purchase another 25 copies. How much more will it cost?
学校图书馆购进30本《格林童话》花了297元，由于供不应求，校长决定再购进25本，还需要多少钱？
<gadget id="calculator">9.9 * 25</gadget>
<output>247.5</output>

<result>247.5</result>