Answer:
Let the dog is walked m miles.
Tonya’s dog-walking service charges a flat rate of $20 per month, plus $3 per mile that each dog is walked.
Equation becomes:
![20+3m](https://img.qammunity.org/2020/formulas/mathematics/middle-school/2aitkula0djwymyfj8eocm3til3t1968hg.png)
Beth does not charge a monthly fee for her dog-walking service, but she charges $5 per mile that each dog is walked.
Equation becomes:
![5m](https://img.qammunity.org/2020/formulas/mathematics/middle-school/cuflom411e0alggca8patxw752o2iv75w8.png)
------------------------------------------------------------------------------------------
Part A:
The equation that can be used to find the number of miles m for which Tonya and Beth would charge the same amount.
![20+3m =5m](https://img.qammunity.org/2020/formulas/mathematics/middle-school/44fbebv7h6wu5mqjr68pwvnvbemwao84z2.png)
Part B:
Solving for m;
![20+3m =5m](https://img.qammunity.org/2020/formulas/mathematics/middle-school/44fbebv7h6wu5mqjr68pwvnvbemwao84z2.png)
![5m-3m=20](https://img.qammunity.org/2020/formulas/mathematics/middle-school/h5ryl4d3as5g5670eq1r63d54lq09puqiz.png)
=>
![2m=20](https://img.qammunity.org/2020/formulas/mathematics/middle-school/uwnxrktv463gtplcwq5vki7lk427qja8wv.png)
=> m = 10
Hence, both would charge the same amount for 10 miles.