Calculate Winning Percentage With Single mySql Query

I have a mySQL database for a pool league and I want to calculate the winning percentage when I SUM the totals after each week. How do I write a statement that will do this? Below is my table and the statement I am using to SUM but it don't calculate the percentage when I add weekly stats.

team | wins | losses | pct

hueys | 5 | 5 | .500

buds | 2 | 8 | .200

fudas | 4 | 6 | .400

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SELECT DISTINCT Team, SUM( Wins ) as Wins, SUM( Losses ) as Losses, Pct

FROM standings

GROUP BY Team

ORDER BY Wins

DESC LIMIT 0 , 500