+26367 If \(a, b, c\) are positive integers less than \(13\) such that
\(\begin{align*} 2ab+bc+ca&\equiv 0\pmod{13}\\ ab+2bc+ca&\equiv 6abc\pmod{13}\\ ab+bc+2ca&\equiv 8abc\pmod {13} \end{align*}\)
then determine the remainder when \(a+b+c\) is divided by \(13\).
answer see: https://web2.0calc.com/questions/help-me_17340
