A storybook has 120 pages. Li Hua reads 15 pages every day for 6 days. How many pages are left?
一本故事书有120页，李华每天看15页，看了6天，还剩多少页没看？
<gadget id="calculator">15 * 6</gadget>
<output>90</output>

<gadget id="calculator">120 - 90</gadget>
<output>30</output>

<result>30</result>