For this case we have as a fact that Tony pays monthly $ 27 for telephone service, in addition to $ 0.04 per minute of additional use.
If "M" represents the number of minutes used by Tony in a month we have:
![27 + 0.04M](https://img.qammunity.org/2019/formulas/mathematics/college/1tae507f2zum11sckf7avzyfrgiyarft5t.png)
If the minimum that has been charged in a month is $ 70.44 then:
![27 + 0.04M \geq 70.44](https://img.qammunity.org/2019/formulas/mathematics/college/3szfwd7i13o2fm0y28ymj5pw12rr8pboh7.png)
Clearing "M" we have:
We subtract 27 on both sides of the inequality:
![27-27 + 0.04M \geq 70.44-27\\0.04M \geq 43.44](https://img.qammunity.org/2019/formulas/mathematics/college/sslu8ajepir1oo435dsc14iofjdxsebdfy.png)
We divide by 0.04 on both sides of the inequality:
![\frac {0.04M} {0.04} \geq \frac {43.44} {0.04}\\M \geq 1086\ minutes](https://img.qammunity.org/2019/formulas/mathematics/college/fn0jkqqpaoh179575d3grajfhu3attwmi4.png)
Tony uses at least 1086 minutes per month.
Answer:
Tony uses at least 1086 minutes per month.