Which condition is required for ax≡b(modn)ax \equiv b \pmod{n}ax≡b(modn) to have exactly gcd(a,n)\gcd(a, n)gcd(a,n) solutions?
gcd(a,n)∣b\gcd(a, n) | bgcd(a,n)∣b
gcd(a,n)=1\gcd(a, n) = 1gcd(a,n)=1
nnn is prime
aaa is prime