Sentence 1: Felix was very good at math but his nephew wasn't. 
 Sentence 3: Felix helped his nephew every day after class for a full month 
 Sentence 4:  When his nephew had a math test, he successfully passed it 
 Sentence 5:  Felix was very proud of him and gave him a calculator as a reward 
 Given Sentence 2: The security guards checked their licenses before letting them in.