Jacob's and Roberto's equations are illustrations of linear functions.
- The equations are: [tex]\mathbf{Jacob: y = 20 + 0.15x}[/tex] and [tex]\mathbf{Roberto: y = 30 + 0.10x}[/tex]
- The number of text messages each person can send for their costs to be the same is 200
(a) The equations
From the question, we have the following highlights
- Jacob's plan: $20 per month + $0.15 per text
- Roberto's plan: $30 per month + $0.10 per text
Let the monthly charge be y and the number of texts be x.
The equations are:
[tex]\mathbf{Jacob: y = 20 + 0.15x}[/tex]
[tex]\mathbf{Roberto: y = 30 + 0.10x}[/tex]
(b) The number of texts to spend an equal amount
This means that:
[tex]\mathbf{y = y}[/tex]
So, we have:
[tex]\mathbf{20 + 0.15x = 30 + 0.10x}[/tex]
Collect like terms
[tex]\mathbf{ 0.15x -0.10x= 30 -20 }[/tex]
[tex]\mathbf{ 0.05x= 10 }[/tex]
Divide both sides by 0.05
[tex]\mathbf{x= 200 }[/tex]
Hence, the number of text messages is 200
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