1. He's a shrewd businessman and has built many successful businesses from scratch by himself.2. School provides you with education to make you smart, and the world helps you become worldly-wise and street smart.
 shrewd worldly-wise street smartShrewd 就是精明，心機深的意思，尤其用來形容生意人，Street smart 就是 "街上的聰明", 形容一個人在社會上做人處事圓融的聰明, 跟 worldly-wise 同意。
Many people in third world countries are living in unsaitary conditions.