Question

A survey of 110 lung cancer patients showed that 70 were cigarette smokers, 60 lived in urban areas, and
35 had hazardous occupations. 40 of the smokers lived in urban areas, 15 of the smokers had hazardous
occupations, and 5 of the smokers lived in urban areas and had hazardous occupations. 10 of the patients
with hazardous occupations neither lived in an urban area nor smoked.
a. How many of the patients living in urban areas had hazardous occupations?
b. How many of those living in the urban areas neither smoked nor had hazardous occupations?

Answer 1