Answer:

Step-by-step explanation:
see the attached figure to better understand the problem
Let
c -----> the cost of some taxi journeys
n ----> the number of miles
we know that
The graph is a line
The equation of a line in slope intercept form is

where
m is the slope
b is the c-intercept (value of c when the value of n is equal to zero)
Observing the graph we have the points
(0,2.5), (5,5.5)
<em>Find the slope</em>
The formula to calculate the slope between two points is equal to
substitute the values
we have
-----> because the point (0,2.5) is the c-intercept
substitute in the equation of slope-intercept form

..........solve it like an equation
Gradient is synonymous to slope.
y = 6x + 5 is an example of a slope-intercept form of a straight-line equationl.
The slope-intercept equation is like this:
y = mx + b
where : m = slope ; b = "y-intercept"
y = 6x + 5
6 is the slope
5 is the y-intercept.
Since slope and gradient are synonymous, 6 is the gradient of the above equation.