Earth is 4:1 and moon is 1:4of earth
Let number of books by astrid's = x
Out of x , 84% are fiction.
So, Number of non fictional books = x - 
= 
→Ratio of number of books to fictional books
⇒[Dividing numerator and denominator by 4.]
→Out of 25 books by astrid 21 are fictional.
→ Number of fictional books by astrid = 
Answer:
{-1, 5} (two real solutions).
Step-by-step explanation:
On the left side we want x^2, not x?
We need to rewrite x? = 4x - 5 in standard form, that is, as a quadratic with x terms in decreasing powers of x:
x^2 - 4x + 5 = 0
This factors easily to (x - 5)(x + 1) = 0.
We let each factor equal zero (0) separately and solve for x:
{-1, 5} (two real solutions).
Not enough info, how many children are there and how many books
So None