The students participated in the afforestation activities. The number of trees planted in the sixth grade was 40 less than that in the fourth grade, 290 trees were planted in the sixth grade, and how many trees were planted in the fourth grade?
同学们参加植树造林活动，六年级种的棵数是四年级的3倍少40棵，六年级种了290棵，四年级种了多少棵？
<gadget id="calculator">290 + 40</gadget>
<output>330</output>

<gadget id="calculator">330 / 3</gadget>
<output>110</output>

<result>110</result>