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.

i think u have 12 apples sorry again i don't really know if it correct i'm just tryna hrlp people out.

the height of the surface increases from the center out to the sides of the road.

step-by-step explanation:

as we move out we move away from the x-axis.

and as mentioned in the problem statement that height of a road increases when we move away from the center x.

hence proved that 3rd option

the height of the surface increases from the center out to the sides of the road.

is the correct option.