There are 25 questions in one exam, 4 points for one correct answer, 0 points for no answer, and 1 point deducted for wrong answer. Xiaolin answered all the questions, but only scored 70 points. How many questions did he answer correctly?
一次考试共有25道题，答对一题得4分，不答得0分，答错倒扣1分，小林答了所有的题目，但只得了70分，他答对了多少题．
<gadget id="calculator">25 * 4</gadget>
<output>100</output>

<gadget id="calculator">100 - 70</gadget>
<output>30</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">30 / 5</gadget>
<output>6</output>

<gadget id="calculator">25 - 6</gadget>
<output>19</output>

<result>19</result>