Problem - 4163
Solve $15x\equiv 7\pmod{32}$.
By Euler theorem, we have $15^{16}\equiv 1\pmod{32}$. Therefore the solution is $$15^{16}\times 7\equiv \left(15^2\right)^7\times 15\times 7\equiv \boxed{9}\pmod{32}$$
Solve $15x\equiv 7\pmod{32}$.
By Euler theorem, we have $15^{16}\equiv 1\pmod{32}$. Therefore the solution is $$15^{16}\times 7\equiv \left(15^2\right)^7\times 15\times 7\equiv \boxed{9}\pmod{32}$$