Answer:
[tex]y = -\frac{220}{3}x + 520[/tex]
Step-by-step explanation:
Given
[tex]x = time[/tex]
[tex]y = distance[/tex]
For the first 3 hours, we have:
[tex](x_1,y_1) = (3,300)[/tex]
At 6 hours, we have:
[tex](x_2,y_2) = (6,80)[/tex]
Required
Express y as a function of x
First, calculate the slope:
[tex]m = \frac{y_2 - y_1}{x_2 - x_1}[/tex]
This gives:
[tex]m = \frac{80 - 300}{6 - 3}[/tex]
[tex]m = \frac{-220}{3}[/tex]
[tex]m = -\frac{220}{3}[/tex]
The equation is then calculated using:
[tex]y = m(x - x_1) + y_1[/tex]
Where:
[tex]m = -\frac{220}{3}[/tex]
[tex](x_1,y_1) = (3,300)[/tex]
[tex]y = -\frac{220}{3}(x - 3) + 300[/tex]
Open bracket
[tex]y = -\frac{220}{3}x + \frac{220}{3}*3 + 300[/tex]
[tex]y = -\frac{220}{3}x + 220 + 300[/tex]
[tex]y = -\frac{220}{3}x + 520[/tex]