A bookstore bought back a children's storybook that sold 25% on the first day, and sold 30 more copies on the second day than on the first day. After two days of selling, there were still 108 unsold books. How many copies of this kind of children's storybook were bought back in total? ?
书店购回一种儿童故事书第一天卖出25%，第二天比第一天多卖了30本，卖了两天后还剩108本没卖，这种儿童故事书共购回多少本？
<gadget id="calculator">108 + 30</gadget>
<output>138</output>

<gadget id="calculator">138 / 0.5</gadget>
<output>276</output>

<result>276</result>