Answer: Hence, our required model will be

Explanation:
Since we have given that
Luana bought a new phone and
For 3 months, the amount she paid = $175
For 6 months, the amount she paid = $295
Now, we have to model an equation ,
Here, let cost be 'C' and
Let number of months be 'm'.
So, we will use the "equation of line" i.e. for two point slope form :
Here y represented by 'C' and x represented by 'm'
So,

Hence, our required model will be
