[tex]\it a=b\cdot2 \Rightarrow a=2b\\ \\ a=c+12 \Rightarrow c=a-12 \Rightarrow c=2b-12\\ \\ a+b+c=68 \Rightarrow 2b+b+2b-12=68 \Rightarrow 5b-12=68|_{+12} \Rightarrow \\ \\ \Rightarrow 5b=80|_{:5} \Rightarrow b=16\\ \\ a=2b=2\cdot16=32\\ \\ c=2b-12=32-12=20[/tex]
Numerele cerute sunt: a = 32, b=16, c=20
