Find all non-negative integers aaa such that gcd(a,60)=12\gcd(a, 60) = 12gcd(a,60)=12.
a∈{12,24,36}a \in \{12, 24, 36\}a∈{12,24,36}
a∈{12,24,36,48}a \in \{12, 24, 36, 48\}a∈{12,24,36,48}
aaa must be a multiple of 12, and gcd(a/12,5)=1\gcd(a/12, 5) = 1gcd(a/12,5)=1
aaa must be a divisor of 60 and a multiple of 12