v汽=45km/h=12.5m/s;
由题意可知,两车间路程关系应为:
v 汽t=v 拖t+200
代入数据得:12.5×30=v 拖×30+200
解得:v 拖=5.8m/s;
答:拖拉机的速度是5.8m/s.