Dongdong reads a story book. On the first day, he reads (1/5) of the whole book. On the second day, he reads 15 pages more than the first day, leaving 75 pages unread. How many pages does this storybook have?
东东看一本故事书，第一天看了全书的(1/5)，第二天比第一天多看15页，还剩75页没有看．这本故事书有多少页？
<gadget id="calculator">75 + 15</gadget>
<output>90</output>

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

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

<gadget id="calculator">90 / (3/5)</gadget>
<output>150</output>

<result>150</result>