Question

how can you say that hampi was an administrative as well as temple town

Answer 1

I can explain it as a temple town 
Hampi was a templw town as temples were the hub of cultural activities in Hampi. The Mahanavami festival was a grand and important festival celebrated in Hampi. There used to be a Mahanavami platform where the king recieved guests and accepted tribute from subordinate chiefs. He also watched music and dance performances.