Mexican billionaire Carlos Slim looks on before he gives a speech at Mexico's school of engineers during an event to mark the 50th anniversary of his engineering degree, in Mexico City

 
Mexican billionaire Carlos Slim looks on before he gives a speech at Mexico
Mexican billionaire Carlos Slim looks on before he gives a speech at Mexico's school of engineers during an event to mark the 50th anniversary of his engineering degree, in Mexico City May 28, 2013. REUTERS/Henry Romero