It’s nothing that a graduate of the school of hard knocks shouldn’t be able to handle, but Jay-Z has seen several of his major investments flounder during the recession, even as much of his $1 billion empire stays strong. The rapper lost $50 million on hotel developments in Manhattan, the Las Vegas branch of his 40/40 Club was closed in late 2008 and a Chicago franchise was aborted, and he walked away from a $2 million investment to develop the Aqueduct Racetrack in New York. The award-winning Broadway musical Fela! has yet to turn a profit, and the New Jersey Nets, which he has a 1.5 percent stake in, have performed poorly. However, Jay-Z’s business remains strong in core music and apparel retail sales, which will likely bring in 10 figures this year. His Rocawear brand is a big seller this spring, in part because the rapper insisted on smaller logos and less baggy pants. Experts say the hip-hop mogul is talented enough to market anything but a breakfast cereal.