The vertical or y axis of the graph shows Sam's distance from the dock while the corresponding time in minutes is represented on the x axis.
The time on the x axis repesents the input. Thus, if we locate 3 on the x axis and trace it vertically to the pont where it touches the line on the graph, the corresponding value on the y axis would be 40. Hence, the correct option is C
After 3 minutes, sam is 40 meters from the dock
We can write the equation representing the function in the slope intercept form which is expressed as
y = mx + c
where
m represents slope
c represents y intercept
Slope = (y2 - y1)/(x2 - x1)
Slope = (60 - 40)/(6 - 3) = 20/3
y intercept is the point where the line cuts across the y axis. From the graph, y intercept, c = 20
By substituting into the slope intercept equation, the equation of the line is
y = 20x/3 + 20
For an input, x = 3,
y = 20 * 3/3 + 20
y = 40