The height of a stack of books, h inches is directly proportional to the number of books, n. The height of a stack of 10 books is 12 inches.

-Find the constant of proportionality

-Write and equation that relates to HandN

-Find the height of a stack of 24 books

Y=kx is the direct variation formula. Inserting the information and variables from this scenario we get h = kn.

12 = k * (10) First solve for 'k', the constant of proportionality by dividing by 10.

1.2 = k

Next write the equation using this k and the h & n.

h = 1.2*n

Now we want to find the height if we have 24 books so plug 24 in for n.

h = 1.2 * 24

h = 28.8 inches