There are 100 tourists going to Longmen to participate in rafting activities, each rubber boat has 2 people, and b rubber boats have already started, how many tourists have not yet started.
有100名游客到龙门参加漂流活动，每条橡皮艇坐了2人，已经出发了b条橡皮艇，还有多少名游客没有出发．
<gadget id="calculator">100 - 2</gadget>
<output>98</output>

<result>98</result>