Xiaoli participates in a math knowledge quiz. There are 20 questions in total, 10 points are awarded for each correct answer, and 5 points are deducted for each wrong answer. Knowing that Xiaoli has answered 13 questions and scored 70 points, ask how many questions Xiaoli answered correctly.
小丽参加一次数学知识抢答赛，一共有20道题，答对一题得10分，答错一题扣5分．已知小丽答了13道题得了70分，问小丽答对了多少道题．
<gadget id="calculator">10 * 13</gadget>
<output>130</output>

<gadget id="calculator">130 - 70</gadget>
<output>60</output>

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

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

<gadget id="calculator">13 - 4</gadget>
<output>9</output>

<result>9</result>