school held a math test with a total of 40 questions. According to the regulations: 3 points for each correct answer; 1 point will be deducted for each wrong answer or no answer. Zhang Hua scored 60 points in this exam. How many questions did Zhang Hua answer correctly? (answer in two ways)
某校举行数学考试，共40道题．按规定：每答对一题得3分；每答错或不答就从得分中扣除1分．张华在这次考试中得了60分，请问张华答对了多少道题？(用两种方法解答)
<gadget id="calculator">40 * 3</gadget>
<output>120</output>

<gadget id="calculator">120 - 60</gadget>
<output>60</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

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

<gadget id="calculator">40 - 15</gadget>
<output>25</output>

<result>25</result>