Hualian Supermarket launched the "Children's Celebration Children's Car Promotion" campaign. On the morning of June 1, half of the total sold was 3 less, and the remaining half was sold in the afternoon by 2 more, and the remaining 12 were not sold. How many baby carriages did Hualian Supermarket prepare for this event?
华联超市展开"庆六一童车促销"活动，6月1日上午售出总数的一半少3辆，下午售出剩下的一半多2辆，还剩12辆没有卖出．华联超市这次活动准备了多少辆童车？
<gadget id="calculator">12 + 2</gadget>
<output>14</output>

<gadget id="calculator">14 * 2</gadget>
<output>28</output>

<gadget id="calculator">28 - 3</gadget>
<output>25</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<result>50</result>