The children are doing exercises on the playground, and Xiaojun is standing in the third row on the left and the eighth row on the right; if counting from front to back, Xiaojun is the 6th, and counting from the back to the front, Xiaojun is the 7th. If the number of people in each row is the same, how many children are doing exercises in total?
小朋友在操场上做操，小俊站在左边第3行、右边第8行；假如从前往后数小俊是第6个，从后往前数小俊是第7个．如果每行的人数相同，那么一共有多少个小朋友在做操．
<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<gadget id="calculator">7 + 5</gadget>
<output>12</output>

<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<gadget id="calculator">12 * 10</gadget>
<output>120</output>

<result>120</result>