Xiaohong reads an interesting math book, and has read 30% of the book, leaving 42 pages unread. How many pages does this book have?
小红看一本趣味数学书，已经看了全书的30%，还剩下42页没有看．这本书一共有多少页？
<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">42 / (7/10)</gadget>
<output>60</output>

<result>60</result>