Let us work on the equation of Data plan A
Let us pick any two data from the information given on Data plan A in order to obtain the equation.
Therefore, the two points picked are
[tex]\begin{gathered} (x_1,y_1)\rightarrow(5,39) \\ (x_2,y_2)\rightarrow(20,99)_{} \end{gathered}[/tex]
The formula to obtain the equation is,
[tex]\frac{y-y_1}{x-x_1}=\frac{y_2-y_1}{x_2-x_1}[/tex]
Hence, the equation of Data plan A is
[tex]\begin{gathered} \frac{y-39}{x-5}=\frac{99-39}{20-5} \\ \frac{y-39}{x-5}=\frac{60}{15} \\ \frac{y-39}{x-5}=4 \end{gathered}[/tex]
Cross multiply
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