There are 660 fifth-grade students, which is more than the fourth grade (1/10), how many are there fourth-grade students?
五年级学生有660人，比四年级多(1/10)，四年级学生有多少人．
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 + (1/10)</gadget>
<output>11/10 = around 1.1</output>

<gadget id="calculator">660 / (11/10)</gadget>
<output>600</output>

<result>600</result>