certain city carried out afforestation activities. 220 trees were planted in the east area, 98 less than in the west area. The number of trees planted in the north area was exactly twice that of the west area. How many trees were planted in the north area?
某市开展植树造林活动，东区植树220棵，比西区少植98棵，北区植的棵数正好是西区的2倍，北区植树多少棵？
<gadget id="calculator">220 + 98</gadget>
<output>318</output>

<gadget id="calculator">318 * 2</gadget>
<output>636</output>

<result>636</result>