Question: What is the birthday of Fernando Romero's billionaire father-in-law?

Related documents: [0]  [DOC] Fernando Romero (born 11 October 1971) is a Mexican architect. He is the son-in-law of Mexican billionaire, Carlos Slim. [END] 
[1]  [DOC] Carlos Slim Helú (] ; born January 28, 1940) is a Mexican business magnate, investor, and philanthropist. From 2010 to 2013, Slim was ranked as the richest person in the world. He derived his fortune from his extensive holdings in a considerable number of Mexican companies through his conglomerate, Grupo Carso. [END]  
Answer: January 28, 1940
January 28, 1940