Bobby had 36 books in his locker. some were library books, some were textbooks, and the rest were telephone books. the number of library books and telephone books combined equals twice the number of textbooks. the number of textbooks and telephone books combined equals three times the number of library books. how many of each type of book were in bobby's locker?

Let x be the libaray books, y be the textbooks and z be the telephone books

x + y + z = 36 ...(1)

x + z = 2y

y =

y + z = 3x ...(3)

Plugging eq 2 into 1 and 3

x +

3x + 3z = 72 ...(4)

x + 3z = 6x

3z - 5x = 0 ...(5)

Subtract eq(4) from 5 and simplfy:

3x - (- 5x) = 72

3x + 5x = 72

8x = 72

x = 9

And, 3z = 5x

3z = 5(9)

z = 15

And, y =

y = 12

Hence, there are 9 libaray books, 12 textbooks and 15 telephone books in the locker.

the formula of a slope:

from a table we have

substitute:

the slope of f(x) is -1.

the graph of funcfion g(x) is a horizontal line. the slope of a horizontal line is equal 0. therefore the slope of g(x) is 0.

-1 < 0

step-by-step explanation:

what grade level is this? need to know so i can look in my old textbooks!