Answer :
You can set it up as a proportion. 21/40 = x/100
Cross multiply 40x= 2100
Divide by 40 to have x alone x=2100/40
solve x= 52.5
The percentage of games won is 52.5%
Cross multiply 40x= 2100
Divide by 40 to have x alone x=2100/40
solve x= 52.5
The percentage of games won is 52.5%