20m/s=20×[(1÷1000)÷(1÷3600)]=20×[(1÷1000)×3600]=20×(36÷10)=720÷10=72km/h
jak by co te podzielic znaki to ułamki:)
b)20m/s=20×60=120m/min
v=s÷t
s=v×t
s=120m/min×10min
s=1200m
a) http://img109.imageshack.us/img109/8485/beztytuugd.png
c) http://img109.imageshack.us/img109/9669/ley.png