For the basic charge (starting value), it is charge at t = 0.
Therefore, the basic charge is $15.67.
Next, let's determine the unit rate charge.
Let,
x₁, y₁ = 0, 15.67
x₂, y₂ = 5.0, 19.98
We get,
[tex]\text{ Unit rate = }\frac{y_2-y_1}{x_2-x_1}=\text{ }\frac{\text{ 19.98 - 15.67}}{\text{ 5.0 - 0}}\text{ = }\frac{\text{ 4.31}}{\text{ 5}}[/tex][tex]\text{ Unit rate = \$0.862}[/tex]Therefore, the unit rate change is $0.862.
The answer is, therefore, letter C : $15.67, $0.862 per therm
