There are a total of 20 questions in the fourth grade mathematics competition of Yale School. It is stipulated that 10 points will be awarded for each correct question, and 5 points will be deducted for each incorrect question. Li Ling scored a total of 140 points in this competition and won the first place. She did How many questions are correct.
雅乐学校四年级数学竞赛题共20题，规定做对一题得10分，做错一题倒扣5分，李玲在这次比赛中一共得了140分，获得了第一名，她做对了多少题．
<gadget id="calculator">20 * 10</gadget>
<output>200</output>

<gadget id="calculator">200 - 140</gadget>
<output>60</output>

<gadget id="calculator">10 + 5</gadget>
<output>15</output>

<gadget id="calculator">60 / 15</gadget>
<output>4</output>

<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<result>16</result>