What is the best and cheap way to HKIA from royal plaza hotel in mongkok in late hour.

You are advised to take shuttle bus no.A22 at Airport (Ground Transportation Centre) and get off at Shanghai Street, Jordan Road. Then take West Rail Line Hung Hom Station and East Rail Line to Mong Kok East Station, Exit D. The whole way takes around 65 mins. And the ticket fare is 46.1 HKD per person. After arriving, walk northeast around 200 yards to find your hotel.