The students visited the science and technology museum. They lined up in 4 rows with the same number of people. Xiaojun was in the 2nd row. He was the 9th person from the front and the 11th person from the back. How many people visited the exhibition?
同学们到科技馆参观，他们排成人数同样多的4行，小军排在第2行，从前数是第9人，从后数是第11人，参观展览有多少人．
<gadget id="calculator">11 - 1</gadget>
<output>10</output>

<gadget id="calculator">9 + 10</gadget>
<output>19</output>

<gadget id="calculator">19 * 4</gadget>
<output>76</output>

<result>76</result>