Answer: 25%
Step-by-step explanation:
Let's take our given numbers
20% you win both checkers and chess against your friend
30% you win against your friend in chess
Now we take both probability's 20% and 30%
We are know working with a probability out of 200%
Let's add 20% and 30%
20%+30%=50%
Now 50% of 200% is
25%