Răspuns :
notam cu x y z numerele
y=2x
z=4x
x+y+z=21=>x+2x+4x=21=>7x=21=>x=3
y=2x
z=4x
x+y+z=21=>x+2x+4x=21=>7x=21=>x=3
a+b+c= 21
a+2b+4c=21
7a=21 / :7
a= 3
3+3×2+4×3=21
3+6+12= 21
b= 6
c= 12
a+2b+4c=21
7a=21 / :7
a= 3
3+3×2+4×3=21
3+6+12= 21
b= 6
c= 12