Answer:
Step-by-step explanation:
The equation of a line is given by

where m is the slope and b is the y-intercept (the point where the line intersects the y-axis).
Now, in our case, the y-intercept is b = 100 and so our equation looks like

and the slope is found by computing rise/run using points (4, 200) and (2, 150)

Hence, the equation of the line is

and the initial value is found at x = 0, which is the y-intercept.
To summarize,
equation: y = 25x + 100
initial value : y = 100.