Answer: and the question?
Step-by-step explanation:
Answer:
The author have to use his/her phone less than 20 hours in a month in order for Don’tTalkMuch's is a deal to be better than TalkLots's is.
Step-by-step explanation:
Call X is the number of hours that the author uses on monthly basis.
Total bill value if the author uses Don’tTalkMuch service is $80 + $1 X.
Total bill value if the author uses TalkLots service is $20 + $4X
The total fees between 2 providers equal as:
$80 + $1 X = $20 + $4X => 3X = $60 => X = 20
Hence: The author have to use his/her phone less than 20 hours in a month in order for Don’tTalkMuch's is a deal to be better than TalkLots's is.
The only solution for
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is
![x=0](https://tex.z-dn.net/?f=x%3D0)
, so it's either
![(0,1)](https://tex.z-dn.net/?f=%280%2C1%29)
or
![(0,-1)](https://tex.z-dn.net/?f=%280%2C-1%29)
.
Both
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and
![3^0](https://tex.z-dn.net/?f=3%5E0)
are equal to 1, so the answer is
![(0,1)](https://tex.z-dn.net/?f=%280%2C1%29)
.