From a survey conducted in a cancer hospital it is found that `10%` of the patients were alcoholics, `30%` chew gutka and `40%` have no specific carcinogenic habits. If cancer strikes `80%` of the smokers, `70%` of alcoholics, `50%` of the non specific, then estimateic the probability that a cancer patient chosen from any one of the above types, selected at random,
has no specific carcinogenic habits.

Answer

`4/(42)`