math
posted by maggie .
MEghan had 36 books in her locker. Some were library books, text books and the rest were telephone books. THe number of library books and phone books combined equals twice the number of text books. The number of text books and telephone books equals three times the number of library books. How many of each kind of book were in Megan's locker?

telephone books  x
textbooks  y
library books 36xy
36xy + x = 2y or 3y = 36
y = 12
y + x = 3(36xy)
y+x = 108  3x  3y
4x + 4y = 108
x+y= 27
but y = 12
so, x + 12 = 27
x = 15
then 361215 = 9
number of telephone books = 15
number of textbooks = 12
number of library books = 9 
gajkwh;reg