Xiaoya reads a story book. She reads (1/4) of the whole book in the first week and (1/5) of the whole book in the second week. She reads 180 pages in two weeks. How many more pages did you read in the first week than in the second?
小雅看一本故事书，第一周看了全书的(1/4)，第二周看了全书的(1/5)，两周一共看了180页．第一周比第二周多看了多少页？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/4) + (1/5)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">180 / (9/20)</gadget>
<output>400</output>

<gadget id="calculator">(1/4) - (1/5)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">400 * (1/20)</gadget>
<output>20</output>

<result>20</result>