1. Euler's phi function

Find ø(19n) in terms of ø(n) if n has no factors of 19.
*ø is Euler's phi function

2. If gcd(a,b)=1 then $\phi(ab)= \phi(a) \phi(b)$

Does this help?

3. i think so. so the answer would be 18ø(n)?
thank you