How were the greeks able to defeat the persians?

In general, it appears that the Greeks were able to defeat the Persians because of their superior battle tactics.

For example:

At Marathon, the Persian attack on the weakened Greek center allowed the strengthened Greek flanks to attack and essentially encircle the Persians.

The greeks were able to defeat the Persians because of their superior battle tactics. Hope this helped!

it is due to the halo effect as the impression of the boy created earlier.on the mind of the principle affected his decision