Răspuns :
a+b+c=490
a×2=b
b×2=c
a+2b+b+b×2×c=490
3a+3b+c=490
3a+3b+c=490
3×3+c=490
490 ÷7=70
a=70
b=70×2
b=140
c=140 ×2
c=280
a+b+c=70+140+280=490
a×2=b
b×2=c
a+2b+b+b×2×c=490
3a+3b+c=490
3a+3b+c=490
3×3+c=490
490 ÷7=70
a=70
b=70×2
b=140
c=140 ×2
c=280
a+b+c=70+140+280=490