SF Express’s freight charges for express shipments in Guangdong Province are as follows: the weight of the express shipment does not exceed 1 kg, and the charge is 12 yuan; if the weight of the express shipment exceeds 1 kg, and the total weight does not exceed 50 kg, the excess part is charged at 2 yuan per kg. Comrade Wang submits a shipment and pays 25 yuan for shipping. What is the weight of Comrade Wang's shipment?
顺丰快递公司对广东省内快件的运费收费标准是：快件重量不超过1千克，收费12元；如果快件重量超过1千克，而总重量不超过50千克，超出部分按每千克2元收费，王同志投一个快件，交运费25元，王同志的快件重量是多少．
<gadget id="calculator">50 - 12</gadget>
<output>38</output>

<gadget id="calculator">38 / 2</gadget>
<output>19</output>

<gadget id="calculator">19 + 1</gadget>
<output>20</output>

<result>20</result>