new batch of diaries arrived at the stationery store. The number of diaries sold last week was 12 less than half of the total; How many diaries are there in this batch?
文化用品店新到一批日记本，上一周售出本数比总数的一半少12本；这一周售出的本数比所剩的一半多12本；结果还有19本．问这批日记本有多少本．
<gadget id="calculator">12 + 19</gadget>
<output>31</output>

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

<gadget id="calculator">31 / (1/2)</gadget>
<output>62</output>

<gadget id="calculator">62 - 12</gadget>
<output>50</output>

<gadget id="calculator">50 / (1/2)</gadget>
<output>100</output>

<result>100</result>