Prove that if $d$ is a common divisor of $a$ & $b$, then $d=\gcd(a,b)$ if and only if $\gcd(a/d,b/d)=1$
Prove that if d is a common divisor of a and b, then $d=\gcd(a,b)$ if and only if $\gcd(a/d,b/d)=1$