Sixth grade students from a certain school go to Phoenix Lake by boat. If each boat takes 8 people, then there will be 4 people left; if each boat takes 9 people, then there will be one boat left. How many people are there in this grade?
某校六年级同学去凤凰湖坐船游玩，如果每条船坐8人，那么会余下4人；如果每条船坐9人，那么会余下一条船．该年级共有多少人？
<gadget id="calculator">4 + 9</gadget>
<output>13</output>

<gadget id="calculator">9 - 8</gadget>
<output>1</output>

<gadget id="calculator">13 / 1</gadget>
<output>13</output>

<gadget id="calculator">13 * 8</gadget>
<output>104</output>

<gadget id="calculator">104 + 4</gadget>
<output>108</output>

<result>108</result>