We have two different plans
x is the number of minutes
y= total cost in dollars
Part A)
Plan 1
y=0.20x
Plan 2
y=0.09x+49.95
Part B
In order that the second plan will be preferable, is when the plan 2 is cheaper so we will have the next inequality
![0.20x>0.09x+49.95](https://img.qammunity.org/2023/formulas/mathematics/high-school/xq1n9i271hnla420p9ro8lm1o3xxl9l1jt.png)
Then we need to solve the inequality
![0.20x-0.09x>49.95](https://img.qammunity.org/2023/formulas/mathematics/high-school/clpzpaak04q1124xc3r0zrq5932nukmw26.png)
![0.11x>49.95](https://img.qammunity.org/2023/formulas/mathematics/high-school/85ty9b14smmrd79w0lwlpidbtqsg4kf7n4.png)
![x>(49.95)/(0.11)](https://img.qammunity.org/2023/formulas/mathematics/high-school/gkaymgserwebg8etzgqzigsunebdpezra7.png)
![x>454.09](https://img.qammunity.org/2023/formulas/mathematics/high-school/u989o5d2iltxzxdvxr5fjjkczusecmec7b.png)
The nearest greater inter is 455
Therefore the minimum number of minutes you would have to use in a month in order for the second plan to be preferable is 455 minutes