1) Gathering the information,
We have 6 teams at the Baseball league
We have 10 teams at the Softball league
The question is about the Probability of Baseball league and kids from the 10 -12 ages
So, we'll have 4 teams on the ages 10 - 12 and: So 4 teams on the denominator.
2)
The Probability of P (B | Y) will be calculated by
P(B|Y)=P(B∩ Y)/P(Y)
P(B∩Y)=3/16
P(Y)=4/16=1/4
P(B|Y)=3/16÷1/4=3/4