ANSWER:
14.7 miles per hour
Explanation:
We have that the speed is given by the following function:
![s=\sqrt[]{18d}](https://img.qammunity.org/2023/formulas/mathematics/college/pkeifdhi4gg0c6xbrqk4144v5uome2s7fg.png)
where s is calculated in miles per hour and d is given in feet, therefore, we substitute and calculate the value of the speed:

The speed of car is 14.7 miles per hour