Pharaoh sells shoes. A pair of shoes is bought for 30 yuan and sold for 20 yuan. The customer came to buy shoes and gave Zhang 50. Pharaoh had no change, so he asked a neighbor to exchange 50 yuan. Afterwards, the neighbor found out that the money was fake, and Lao Wang compensated the neighbor another 50. May I ask how much Lao Wang lost in total?
老王是卖鞋的，一双鞋进价30元，甩卖20元，顾客来买鞋给了张50，老王没零钱，于是找邻居换了50元．事后邻居发现钱是假的，老王又赔了邻居50．请问老王一共亏了多少？
<gadget id="calculator">50 - 20</gadget>
<output>30</output>

<gadget id="calculator">30 + 30</gadget>
<output>60</output>

<result>60</result>