The Young Pioneers participated in tree planting activities. The fifth grade planted 123 trees, the fourth grade planted 21 more trees than the fifth graders, and how many trees were planted in the fourth grade?
少先队员参加植树活动，五年级植树123棵，四年级比五年级子多植树21棵，四年级植树多少棵？
<gadget id="calculator">123 + 21</gadget>
<output>144</output>

<result>144</result>