Hello!
The answer is: 75 miles.
Why?
We can solver it solve it by using the following kinematic equation:
![x=xi + v*t](https://img.qammunity.org/2020/formulas/physics/middle-school/u2h7lhrtpnvi3x98m736rvr4y15qrxzkkf.png)
Assuming the starting point as 0 (it's our reference point), let's substitute the given information:
![x=0+50*1.5=75 miles](https://img.qammunity.org/2020/formulas/physics/middle-school/ss5w33jie25ei6lca19pbf5irumvuulvvn.png)
So, Bobs displacement is 75 miles.
Have a nice day!