Exercise 14 Page 244

We know that the amount of liquid fertilizer made depends on the amount of powdered fertilizer used, so different amounts of powdered fertilizer will never make the same amount of liquid fertilizer. Let's confirm this with a table of values.

Table

Following the recipe for making fertilizer, every time we mix $8$ teaspoons of powder with water, we make $5$ gallons of fertilizer.

Teaspoons of Powder, $p$	Gallons of Liquid, $\ell$
$0$	$0$
$8$	$5$
$16$	$10$
$24$	$15$

A function is a relationship that pairs each input value with exactly one output value. We can see from the table that the amount of fertilizer made is a function of the amount of powder used.