We will solve as follows:
a)
We can see that after each hour the distance will increase by 75 miles.
b)
We calculate the slope as follows:
We can see that the graph passes by the points (0, 0) & (1, 75), now we replace in the following expression:
![m=(y_2-y_1)/(x_2-x_1)](https://img.qammunity.org/2023/formulas/mathematics/high-school/78uaqhwt0aws3qfwxigaftpihnmb1gzxtp.png)
Now, we replace:
![m=(75-0)/(1-0)\Rightarrow m=75](https://img.qammunity.org/2023/formulas/mathematics/college/7otdmtj6oy4kpcejyqp74beter2wvadahc.png)
So, the slope is 75.