There are many desks in the classroom, all neatly arranged, the number of desks in each column is equal, and the number of desks in each row is equal. Xiaoqiu's desk is the 4th from the front, and the 4th from the back. There are 4 on his left, No on the right. How many desks are there in Xiaoqiu's classroom?
教室里有很多桌子，都整齐地排列着，每列桌子数相等，每排的桌子数相等，小秋的桌从前面数第4张，从后面数第4张，他的左边有4张，右边没有，小秋的教室一共有多少张桌子．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">4 + 3</gadget>
<output>7</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">7 * 5</gadget>
<output>35</output>

<result>35</result>