A story book, if you read (3/4) of the total pages, there are 75 pages left, if you read (2/5) of the total pages, how many pages are left?
一本故事书，如果读了总页数的(3/4)，还剩75页，如果读了总页数的(2/5)，还剩多少页？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">75 / (1/4)</gadget>
<output>300</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">300 * (3/5)</gadget>
<output>180</output>

<result>180</result>