Problem - 2638
Solve $17x\equiv 229\pmod{1540}$.
The answer is $\boxed{x\equiv 557\pmod{1540}}$.
This is a standard mod equation and thus has a standard solution. Please see the book Number Theory (MOD) .
$$\begin{array}{}
17x &\equiv 229 &\pmod{1540} &\implies 17x &= 229 + 1540y \\
& & &\implies 0 &\equiv 8 + 10y &\pmod{17}\\
& & &\implies 7y &\equiv 8 &\pmod{17}
\end{array}$$
$$\begin{array}{}
\therefore\quad 7y &= 8 + 17u & &\implies 0 &\equiv 1 + 3u&\pmod{7}\\
&&&\implies 3u &\equiv -1 &\pmod{7} \\
&&&\implies u&\equiv 2 &\pmod{7}
\end{array}$$
Therefore:
$$\begin{array}{}
y\equiv \frac{8+17\times 2}{7}&\pmod{17} &\implies y \equiv 6&\pmod{17}\\
x\equiv \frac{229 + 1540\times 6}{1540}&\pmod{1540} &\implies x \equiv 557&\pmod{1540}
\end{array}$$