To find out how much all the pizzas cost, we first need to determine how many total slices the players will eat.
There are 20 players on the team, and each player is supposed to eat 3 slices of pizza. Therefore, the total number of slices needed is:
\[ 20 , \text{players} \times 3 , \text{slices/player} = 60 , \text{slices} \]
Next, we know that each extra large pizza has 10 slices. To find out how many pizzas we need, we divide the total number of slices by the number of slices per pizza:
\[ \frac{60 , \text{slices}}{10 , \text{slices/pizza}} = 6 , \text{pizzas} \]
Now, we need to calculate the cost of these 6 pizzas. Given that each pizza costs $17, the total cost can be calculated as follows:
\[ 6 , \text{pizzas} \times 17 , \text{dollars/pizza} = 102 , \text{dollars} \]
Therefore, the total cost for all the pizzas is:
\[ \boxed{102} \]