解:S=60000m=60km,S1=1500m=1.5km,S2=S-S2=60km-1.5km=58.5km,v1=30km/h,v2=45km/h
t1=S1/v1=1.5km/30km/h=0.05h,
t2=S2/v2=58.5km/45km/h=1.3h
t=t1+t2=0.05h+1.3h=1.35h
v=S/t=60km/1.35h=44.44km/h
答:汽车从甲地到乙的平均速度为44.4km/h 。
v=s/t=60/(1.5/30+58.5/45)=44.44...km/h
首先把单位全部统一为KM,60/[1.5/30+(60-1.5)/45]=44又4/9.
不过个人觉得你把15000写成1500,如果是这样的话,60/[15/30+(60-15)/45]=40