Answer:
![y=-(3)/(4)x+36](https://img.qammunity.org/2021/formulas/mathematics/high-school/melprf1kguxb5go19jyqkhhxy7j57q1lu4.png)
Explanation:
Givens
- The railing will begin at 36 inches height.
- The slant decreases 9 inches for every 12 horizontal inches.
According to the problem, the slant is
![m=-(9)/(12)=-(3)/(4)](https://img.qammunity.org/2021/formulas/mathematics/high-school/sb937inp40xir7mns3hyq8zva56grv2bzt.png)
The initial condition of the function is 36, which is a constant. Also, the slant is negative, because the problem states that "decreases".
If we see the problem form the perspective of a linear function, the constant ratio of change would be the slant.
Therefore, the linear function that models this problem is
![y=-(3)/(4)x+36](https://img.qammunity.org/2021/formulas/mathematics/high-school/melprf1kguxb5go19jyqkhhxy7j57q1lu4.png)
So, the answer is the first choice.