Xiao Ming reads a book, he reads 16 pages a day, half of the book in 10 days, and then he reads 4 more pages a day than before, how many days did it take to finish reading this book?
小明读一本书，他每天读16页，10天读了全书的一半，此后他每天比原来多读4页，读完这本书一共用了多少天？
<gadget id="calculator">16 + 4</gadget>
<output>20</output>

<gadget id="calculator">10 / 20</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">16 * (1/2)</gadget>
<output>8</output>

<gadget id="calculator">10 + 8</gadget>
<output>18</output>

<result>18</result>