Xiaohua solves a math problem. She gets 4 points for a correct answer and deducts 4 points for a wrong answer. She answered 20 questions and only scored 56 points. How many questions did Xiaohua get right?
小华解数学题，答对一题加4分，答错扣4分，她答了20道，结果只得了56分，小华答对了几道？
<gadget id="calculator">20 * 4</gadget>
<output>80</output>

<gadget id="calculator">80 - 56</gadget>
<output>24</output>

<gadget id="calculator">4 + 4</gadget>
<output>8</output>

<gadget id="calculator">24 / 8</gadget>
<output>3</output>

<gadget id="calculator">20 - 3</gadget>
<output>17</output>

<result>17</result>