David is having a pool party at his house. There are b number of boys at the party and the average of their ages is g. There are g number of girls at the party and the average of their ages is b. The sum of the boy's ages is 15. The average age of everyone at the party (all the boys and girls, plus David's 42-year old father) is b + g. What is the value of b + g? A. 12 B. 10 C. 9 G D. 8 ​

true statements:

a) x + y = y + x   ⇒ commutative property of addition

b) (x * y) * z = x * (y * z) ⇒ associative property of multiplication

d) (x + y) + z = x + (y + z) ⇒ associative property of addition

false statements:

c) x - y = y - x   should be: x - y = - y + x

e) (x - y) - z = x - (y - z) should be: (x - y) - z = x - (y + z)

step-by-step explanation:

ab will be equal to

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