Answer:
![39+0.15m \leqslant 50](https://img.qammunity.org/2020/formulas/mathematics/high-school/x2e0ran0pc5p3xlvi4swao0bvqahqkswod.png)
Explanation:
From the question, Diana wants her total bill to be less than $50.
Diana pays a fixed monthly bill of
$39 for her mobile phone and an additional
$0.15 per minute for phone internet service.
The bill Diana pays for m minutes of using the internet is $0.15m in a month.
The total monthly bill becomes,
![39+0.15m](https://img.qammunity.org/2020/formulas/mathematics/high-school/8v2kyygchnqxukwsn7jfqp8ylh79ukycap.png)
The maximum bill she wants to pay is $50.
![\implies39+0.15m \leqslant 50](https://img.qammunity.org/2020/formulas/mathematics/high-school/msi6fkag0avejarx207ehj3xsnu3ncwjqx.png)
This inequality can be solved to determine the number of available minutes.