Have you considered drawing a tree diagram? It should make the 1-step calculation very obvious.

P(woman)=0.6

P(if woman, smokes)=0.3

Assume there are 100 people. Then, there are 40 men and 60 women. 30% of these 60 women smoke, out of the total 100. A quick calculation leads to 18 out of the 100 people being female smokers.