A story book, Xiaohong read the whole book (2/15) on the first day, read the whole book (1/4) on the second day, and read the whole book less than the total sum of the previous two days on the third day ( 1/5), what percentage of the book was read on the third day?
一本故事书，小红第一天看了全书的(2/15)，第二天看了全书的(1/4)，第三天看的比前两天的总数和少了全书的(1/5)，第三天看了这本书的几分之几？
<gadget id="calculator">2 / 15</gadget>
<output>2/15 = around 0.133333</output>

<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>1/20 = around 0.05</output>

<gadget id="calculator">(2/15) + (1/20)</gadget>
<output>11/60 = around 0.183333</output>

<result>11/60 = around 0.183333</result>