Answer:
Part 1) The rate of change is

Part 2) The initial value is 100 km
Part 3) His distance increases 60 kilometers every hour
Explanation:
Part 1) Find the rate of change
The rate of change is the same that the slope
Let
x ----> the time in hours
y ---> the distance in kilometers
we know that
The formula to calculate the slope between two points is equal to

we have the points
(0,100) and (10,700)
substitute in the formula



Part 2) Find the initial value
we know that
The initial value or y-intercept is the value of y when the value of x is equal to zero
Looking at the graph
For x=0
The value of the y-coordinate is 100
therefore
The initial value is 100 km
Part 3)
we know that
The slope or unit rate is

That means
His distance increases 60 kilometers every hour