Question

If gcd(a,b)=1 then prove that gcd(ac,b)=gcd(c,b)

Answer 1

HINT: (a,b) = 1 means that there is some x and y such that ax + by = 1

perhaps start by writing d=gcd(ac,b) and e=gcd(b,c) and then show that d|e and e|d