Xiaoqiang borrowed a 320-page storybook from the library and read 15 pages a day for 13 days. How many pages are there yet?
小强从图书馆借了一本320页的故事书，每天看15页，看了13天．还有多少页没有看？
<gadget id="calculator">15 * 13</gadget>
<output>195</output>

<gadget id="calculator">320 - 195</gadget>
<output>125</output>

<result>125</result>