I'm having trouble on my math and i can't figure it out. the problem is: among the fifty children at the book fair, b of them are boys. 30% of the girls at the book fair are younger than 12 years old, while 40% of the boys are at least 12 years old. how many children at the book fair are younger than 12 years old?
what do i

Girls= g
boys=b
50=g+b
Now we know that 30% of the girls are younger than 12. That's already half to answer...
We also know that 40% of the boys are OLDER than 12, which leaves 60% of the boys YOUNGER than 12.
This makes us know that 30%+60% out of 50 kids are younger than 12
30%+60%=90%

90% of the kids are younger than 12 
90% of 50 is 45

ANSWER: 45 kids are younger than 12

What's the denominator

B.the point lies directly on the regression