Dongshan Primary School has 3 classes for the fourth grade, 4 classes for the fifth grade, and 2 classes for the sixth grade. There are 45 students in each class of fourth grade, 42 students in each class of fifth grade, and 48 students in each class of sixth grade. How many more students are in the fourth grade than the sixth grade?
东山小学四年级有3个班，五年级有4个班，六年级有2个班．四年级每班45人，五年级每班42人，六年级每班48人．四年级比六年级多多少人？
<gadget id="calculator">45 * 3</gadget>
<output>135</output>

<gadget id="calculator">48 * 2</gadget>
<output>96</output>

<gadget id="calculator">135 - 96</gadget>
<output>39</output>

<result>39</result>