Răspuns :
a+b+c=21
b=2a
c=4a
a,b,c=?
a+2a+4a=21
7a=21 => a=21:7 => a=3
b=2x3 => b=6
c=4x3 => c=12
verificam : 3+6+12=21
b=2a
c=4a
a,b,c=?
a+2a+4a=21
7a=21 => a=21:7 => a=3
b=2x3 => b=6
c=4x3 => c=12
verificam : 3+6+12=21
a+b+c=21
a=!__!
b= !__!__!
c= !__!__!__!__!
21:7=3-primul numar
b=3×2=6-al doilea nr
c=3×4=12-al treilea nr
Proba:3+6+12=21
a=!__!
b= !__!__!
c= !__!__!__!__!
21:7=3-primul numar
b=3×2=6-al doilea nr
c=3×4=12-al treilea nr
Proba:3+6+12=21