In an experiment to study the dependence of hypertension on smoking habits ...

In an experiment to study the dependence of hypertension on smoking habits, the following data were taken on 180 individuals:
Non-smokers Moderate Smokers Heavy Smokers
Hypertension 21 36 30
No hypertension 48 26 19
Test the hypothesis that the presence or absence of hypertension is independent of smoking habits. Use a 0.05 level of significance.