If a,b,c are integers from the set of positive integers less than 7 such that then what is the remainder when a+b+c is divided

If a,b,c are integers from the set of positive integers less than 7 such that\(\begin{align*} abc&\equiv 1\pmod 7,\\ 5c&\equiv 2\pmod 7,\\ 6b&\equiv 3+b\pmod 7, \end{align*}\)then what is the remainder when a+b+c is divided by 7?