Answer:
A function rule for the relationship between the amount of plant food remaining, f(x), and the number of days that have passed, x is ![f(x)=72-12x](https://tex.z-dn.net/?f=f%28x%29%3D72-12x)
Step-by-step explanation:
We are given that Ryan used 72 mL of food over the course of a 6 day study.
So, He used amount per day = ![\frac{72}{6}](https://tex.z-dn.net/?f=%5Cfrac%7B72%7D%7B6%7D)
He used amount per day =12 ml/day
Now we are given that t the amount of plant food remaining decreased an equal amount each day, and he used the entire 72 milliliters by the end of his study.
So, The equation becomes : f(x)=72-12x
f(x):The amount of plant food remaining
x : The number of days that have passed
Hence a function rule for the relationship between the amount of plant food remaining, f(x), and the number of days that have passed, x is ![f(x)=72-12x](https://tex.z-dn.net/?f=f%28x%29%3D72-12x)