% of people who reads A only =25−8=17% % of people who read B only =20−8=12% % of people from A only who read advertisement =17×0.3=5.1% % of people from B only who read advertisement =12×0.4=4.8% % of people from A&B both who read advertisement =8×0.5=4% ∴ total % of people who read advertisement =5.1+4.8+4=13.9%