The bookstore shipped 400 children's story books, 20% of which were sold on the first day, and 150% of the first day's sales on the second day. How many story books are left unsold.
书店运来一种儿童故事书400本，第一天卖了20%，第二天卖的相当于第一天的150%．还剩下多少本故事书没卖．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">400 * (1/5)</gadget>
<output>80</output>

<gadget id="calculator">150 / 100</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">80 * (3/2)</gadget>
<output>120</output>

<gadget id="calculator">80 + 120</gadget>
<output>200</output>

<gadget id="calculator">400 - 200</gadget>
<output>200</output>

<result>200</result>