Several students took the Chinese test. If Zhao Feng’s score increased by 13 points, their average score would reach 90 points. If Zhao Feng’s score decreased by 5 points, their average score would only be 87 points. How many of these students are there in total?
有几位同学参加语文考试，赵峰的得分如果再提高13分，他们的平均分就达到90分，如果赵峰的得分降低5分，他们的平均分就只得87分，那么这些同学共有多少人．
<gadget id="calculator">13 + 5</gadget>
<output>18</output>

<gadget id="calculator">90 - 87</gadget>
<output>3</output>

<gadget id="calculator">18 / 3</gadget>
<output>6</output>

<result>6</result>