The number of students in the third grade is more than that of the fourth grade (1/7), and the number of students in the fourth grade is much less than that of the third grade.
三年级学生人数比四年级多(1/7)，四年级的学生人数比三年级少多少．
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 + (1/7)</gadget>
<output>8/7 = around 1.142857</output>

<gadget id="calculator">70 * (8/7)</gadget>
<output>80</output>

<gadget id="calculator">80 - 70</gadget>
<output>10</output>

<gadget id="calculator">10 / 80</gadget>
<output>1/8 = around 0.125</output>

<result>1/8 = around 0.125</result>