There are 3 classes in the second and third grades of elementary school. There are 75 people in the three grades, and 45 people in each of the two classes of the fourth grade. How many students are there in the third and fourth grades of Yanggang Primary School?
小学二、三年级共有3个班．三个级有75人，四年级两个班各有45人．阳刚小学三、四年级一共有学生多少人？
<gadget id="calculator">45 * 2</gadget>
<output>90</output>

<gadget id="calculator">90 + 75</gadget>
<output>165</output>

<result>165</result>