According to a recent survey 31% of residents of a certain state you're 25 years or older have a bachelors degree. A random sample of 50 residents of the state H 25 years or older will be selected let the random variable B represent the number in the sample who have a bachelors degree what is the probability that B will be exactly 20

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?