Răspuns :
a+b+c=57
a=b-1
c=b+1
b-1+b+b+1=57
3b=57
b=57÷3
b=19
a=19-1
a=18
c=19+1
c=20
v:18+19+20=57
r: 19
a=b-1
c=b+1
b-1+b+b+1=57
3b=57
b=57÷3
b=19
a=19-1
a=18
c=19+1
c=20
v:18+19+20=57
r: 19