Answer: 
Step-by-step explanation:

Answer:
Animal books make up (3/20) of all books
Step-by-step explanation:
Let X be the total number of books, made up of nonfiction, animal, and all others.
(3/5)X are nonfiction books.
Of the nonfiction books, 1/4 are animal books: (3/5)*(1/4)X = (3/20)X are animal books
[This means that Nonfiction, less animal books is: (3/5)X - (3/20)X]
Animal books make up (3/20) of all books.
Answer:
3
Step-by-step explanation:
Answer:
9990 years
Step-by-step explanation:
The exponential function with given values filled in can be solved for the unknown using logarithms.
__
Q(t) = 12 = 36e^(-0.00011t)
1/3 = e^(-0.00011t) . . . . . . divide by 36
ln(1/3) = -0.00011t . . . . . . take natural logs
t = ln(1/3)/(-0.00011) . . . . divide by the coefficient of t
t ≈ 9990 . . . years
Answer:
275
Step-by-step explanation:
1000-725=275