Proofs...

[Caldus]

I would greatly appreciate if someone just at least put me in the right direction with this. I have to prove this:

Prove that of a,b,c are natural numbers, gcd(a,c) = 1 and b divides c, then gcd(a,b) = 1.

[matt grime]

Write down the defintion of gcd, what properties does gcd have, in particular gdc(x,y) and dividing x and y. Consider if d is a divisor of b then is it a divisor of c?