How to speak fluently on basic topics

In a committee,50 people speak French,20 speak Spanish and 10 speak both Spanish and French.How many speak at least one of these two languages?

In a committee, 50 people speak Hindi, 20 speak English and 10 speak both Hindi and English . How many speak at least one of these two languages ?

You are participating in a school debate on the topic 'Roles of advertising for the business & society'. You have to speak against the topic, i.e., on negative fallouts/objectives against advertising. Support your topic point wise.