[tex]\it \left.\begin{aligned}a+b=23|_{\cdot5} \Rightarrow 5a+5b=115\\ \\ b+c=31|_{\cdot2} \Rightarrow 2b+2c=62 \end{aligned}\right\}\ \stackrel{+}{\Longrightarrow}\ 5a+7b+2c=115+62=177[/tex]
