The equation that models the amount of gas left in the car as Phan drives is [tex](g = 18 - 2h)[/tex] and the total amount of gasoline does it take to fill her tank is 18 gallons.
Given :
The following steps can be used in order to determine the equation that models the amount of gas left in the car as Phan drives and the total amount of gasoline:
Step 1 - The two-point form of the line can be used in order to determine the equation that models the amount of gas left in the car as Phan drives.
[tex]\dfrac{y-y_1}{x-x_1}=\dfrac{y_2-y_1}{x_2-x_1}[/tex]
Step 2 - Now, substitute the value of [tex](x_1,y_1)[/tex] and [tex](x_2,y_2)[/tex] in the above expression.
[tex]\dfrac{g-12}{h-3}=\dfrac{8-12}{5-3}[/tex]
Step 3 - Simplify the above equation.
[tex]\begin{aligned}\\(g - 12)&=-2(h-3)\\g - 12&=-2h+6\\g &= 18-2h\\\end{aligned}[/tex]
Step 4 - Now, substitute the value of (h = 0) in the above equation.
[tex]g = 18-2(0)\\g = 18 \; {\rm gallons}[/tex]
Therefore, the correct option is A).
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