The students are doing exercises. Xiaohong stands in the fifth row from the left and the seventh row from the right. She is the sixth from the front and the fourth from the back. The number of people in each row and column is the same. How many people do the exercises?
同学们做操，小红站在左起第5行，右起第7行，从前面数是第6个，从后面数是第4个，每行每列的人数同样多．做操的一共有多少人？
<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<gadget id="calculator">5 + 6</gadget>
<output>11</output>

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

<gadget id="calculator">6 + 3</gadget>
<output>9</output>

<gadget id="calculator">11 * 9</gadget>
<output>99</output>

<result>99</result>