20:2=10 l (jumatate)
10l=10000ml
10000ml: 250ml=40 sticle de un sfert
20-10=10l (rest)
10:2=5 l (rest)
5l=5000ml
5000ml:500ml=10 sticle de 500ml
5000+10000=15000 ml (s-au pus în total)
20l=20000 ml ( cati ml au 20l )
20000-15000=5000ml (au ramas)
5000ml :1000ml=5 sticle (de 1l)
5+10+40=55 sticle