Belgium National - Multi Country Visit

Hello,

I am a Belgium national in the U.S. with a work Visa. I am planning a multi country trip. I will depart from the U.S. and travel to Mumbai, India. From Mumbai, I will travel to Singapore and then from Singapore to Beijing for only 48 hours and then back to the US. Does the 72 hour apply for this trip or should the Beijing portion of the trip occur prior to the Singapore portion of the trip?