Obviously read a story book, read 49 pages in the first week, and left 30% unread. How many pages are there in this storybook? (solution by equation)
明明读一本故事书，第一周读了49页，还剩下30%没有读．这本故事书一共多少页？(用方程解)
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">49 / (7/10)</gadget>
<output>70</output>

<result>70</result>