Answer:
B
Step-by-step explanation:
start by multiplying the 6a to each number in the other set of parenthesis.
after doing so, you end up with the numbers:
and 
now multiply the one to each number in the other parenthesis. you get this:
and
.
then set it all next to each other: 
+

then combine like terms (-54a and 2a) you get: 
so that is how you get B for the answer
We have a total of 10 boys & 8 Girls, then the sample space consist of 18 elements.
P(selecting 1 boy) = (total number of boys/by 18) = P(boy)=10/18=5/9