Archibald and his brother are playing tennis against each other. Archibald has won 12 games and his brother has won 18. What percentage of games has Archibald won?
They have played 30 total games because 12 + 18 = <<12+18=30>>30
The proportion won by Archibald is .4 because 12 / 30 = <<12/30=.4>>.4
The percentage he has won in 40% because .4 x 100% = 40%
#### 40