numarul total de rate salbatice
l______l______l______l______l
se odihnesc l______l (4-1=3 segmente ramase)
innoata l______l (3-1=2 segmente ramase)
construiesc cuibul l______l (2-1=1 segment ramas)
restul = 1 segment=3 rate isi curata penele
l______l = 3 rate
totalul 3 x 4=12 rate salbatice in total au poposit pe lac