There are 450 students in the third grade, and 1.5 times the number in the fourth grade. How many students are there in the third and fourth grades?
三年级有450名学生，四年级人数是三年级的1.5倍，三、四年级共有学生多少人？
<gadget id="calculator">450 * 1.5</gadget>
<output>675</output>

<gadget id="calculator">675 + 450</gadget>
<output>1_125</output>

<result>1_125</result>