28=s/(2s/3v+s/60)
=s/[s(2/3v+1/60)]
=1/(2/3v+1/60)
等号两边同时变为它的倒数
所以有
1/28=2/3v+1/60
1/28-1/60=2/3v
1/v=(1/28-1/60)/(2/3)
=1/35
所以v=35
28=s/(2s/3v+s/60)
=s/[s(2/3v+1/60)]
=1/(2/3v+1/60)
等号两边同时变为它的倒数
所以有
1/28=2/3v+1/60
1/28-1/60=2/3v
1/v=(1/28-1/60)/(2/3)
=1/35
所以v=35