Which city state founded the delian league

Athens

The Delian League (or Athenian League) was an alliance of Greek city-states led by Athens and formed in 478 BCE to liberate eastern Greek cities from Persian rule and as a defence to possible revenge attacks from Persia following the Greek victories at Marathon, Salamis, and Plataea in the early 5th century BCE. (from www.ancient.eu)

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explanation:

learned it in 6th

the government closely monitored its finances to avoid another financial collapse.