Yukou enjoys reading science-fiction. It is the New Year and he has made a resolution to read a book every week for this year. He has a collection of monster books and space travel books in the ratio of 4:5. He presently has 20 space travel books. How many more books (of each genre) does he need to buy to keep his resolution, without changing the ratio?
Choose the correct answer
A) 6 monster, 10 space	B) 8 monster, 10 space	C) 8 monster, 9 space	D) 4 monster, 10 space	E) 7 monster, 12 space
There are 52 weeks in a year. Youku has 20 space travel books, so 4:5 is 4/5:1 means (4/5)(20) = 16 monster books. So, he has   20 + 16= 
<gadget id="calculator">  20 + 16</gadget>
<output>36</output>
36 books. Youku needs  52 - 36= 
<gadget id="calculator"> 52 - 36</gadget>
<output>16</output>
16 more books.   Keeping with the ratio of 4:5 and allowing for the fact that we can not have a fraction of a book, the minimum ratio that satisfies these restrictions is 8:10 giving 18 books, of which 8 are monster books and 10 space travel books.   Answer: 8 monster, 10 space
<result>B</result>
Yukou enjoys reading science-fiction. It is the New Year and he has made a resolution to read a book every week for this year. He has a collection of monster books and space travel books in the ratio of 4:5. He presently has 20 space travel books. How many more books (of each genre) does he need to buy to keep his resolution, without changing the ratio?