On Children's Day on June 1st, bookstores sold 2,500 children's books, 100 more than six times the adult books sold. How many adult books were sold on this day?
"六一"儿童节那天，书店售出少儿图书2500本，比售出的成人图书的6倍还多100本，这一天售出成人图书多少本？
<gadget id="calculator">2_500 - 100</gadget>
<output>2_400</output>

<gadget id="calculator">2_400 / 6</gadget>
<output>400</output>

<result>400</result>