The first sentence is irrelevant information, you can ignore that!
There are 20 players. Each player paid the same amount.
In total, they payed $500,000.
We need x, the amount a single player pays. x times 20 will give us 500,000. This gives us the equation 20x=500,000
Divide both sides by 20 to isolate the variable.
x=25,000