Given:
Given that the graph of Bill's Boffo Bagel.
We need to determine the unit rate for Bill's Boffo Bagel.
Unit rate:
The unit rate can be determined using the formula,
![m=(y_2-y_1)/(x_2-x_1)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/e9lgdayfzr27dyurvzbw9lffpiv7535tiv.png)
Let us substitute any two coordinates that the line passes through the points in the graph.
Substituting the coordinates (2,7) and (4,14) in the above formula, we get;
![m=(14-7)/(4-2)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/4x71c081t740dfmlf98fjezzva59qba33z.png)
Simplifying, we get;
![m=(7)/(2)](https://img.qammunity.org/2021/formulas/mathematics/high-school/t13l9uvu9kf1ljq4ffv0g4hicfq6d4w7y8.png)
![m=3.5](https://img.qammunity.org/2021/formulas/mathematics/high-school/g5o1abfiowhyxqhne1493k2e61gw8dy98u.png)
Therefore, the unit rate for Bill's Boffo Bagel is $3.5.
Hence, the unit rate is $3.50 for 1 bagel.
Thus, Option b is the correct answer.