In the tree planting activities, the number of trees planted in the fourth grade is three times that of the third grade, and 225 trees are planted in the fourth grade. How many trees are planted in the two grades?
在植树活动中，四年级植树的棵数是三年级的3倍，四年级植树225棵，两个年级共植树多少棵？
<gadget id="calculator">225 / 3</gadget>
<output>75</output>

<gadget id="calculator">75 + 225</gadget>
<output>300</output>

<result>300</result>