1/30 of the US population lives in LA County.
1/8 of the US population lives in California.
What fraction of people that live in California live in LA County?
Let US population = P
Put (1/30)P = Lap – number of people living in LA county.
Put (1/8)P = Cp – number of people living in California.
Fraction of LA county people (living) in California = Lap/CP
Fraction = (1/30)P / (1/8)P
Fraction = (1/30) / (1/8)
Fraction = 8/30 = 4/15
Answer: 4/15 of the population of California live in LA County