最佳答案:Dear Mr.Wang,We haven't seen each other for ages. How is everything going with y
最佳答案:(1)设该校参加科技夏令营的学生共有x人,由题意得:2000x×80%=2000(x+3)×70%,解得:x=21,答:该校参加科技夏令营的学生共有21人;(2