Răspuns :
x/2 - I
x-x/2=x/2 - rest
x/2*1/4=x/8 +7- II
20 - III
x/2+x/8+7+20=x
4x+x+56+160=8x
216=8x-5x
x=216:3
x=72 medalii s-au oferit initial
72:2=36 medalii prima competitie
72-36=36 rest
36:4=9 +7=16 medalii a2a competitie
20 medalii a3a competitie
x-x/2=x/2 - rest
x/2*1/4=x/8 +7- II
20 - III
x/2+x/8+7+20=x
4x+x+56+160=8x
216=8x-5x
x=216:3
x=72 medalii s-au oferit initial
72:2=36 medalii prima competitie
72-36=36 rest
36:4=9 +7=16 medalii a2a competitie
20 medalii a3a competitie