Răspuns :
Răspuns:
a+b+c=21
b=a/2
c=a/4
a+a/2+a/4=21 amplificam
4a+2a+a=84
7a=84
a=84:7
a=12
b=12:2=6
c=12:4=3
Răspuns:
/-----/-----/-----/-----/
/-----/-----/
/-----/
a=primul nr.
b=Al doilea
c=Al treilea
a+b+c=21
c=21:7=3
a=3×4=12
b=12:2=6
Verificare:
3+12+6=15+6=21 (corect)