The school organizes "June 1" garden activities. In the guessing game, 80 prizes were issued, and the remaining 12 entertainment items issued an average of 35 prizes for each item, and the prizes were all distributed. How many prizes did the school prepare in total?
学校组织"六一"游园活动．在猜谜游戏中发出奖品80份，其余12个娱乐项目平均每项发出奖品35份，奖品正好全部发完．学校共准备了多少份奖品？
<gadget id="calculator">35 * 12</gadget>
<output>420</output>

<gadget id="calculator">420 + 80</gadget>
<output>500</output>

<result>500</result>