Answer:
a) 
And we want to find a function:

We can find the slope with this formula:

And then we can use the point
to find the intercept
and we got:


So then the linear function is given by:

b) For this case we have that m = 475 so we can replace into the function to find the cost like this:

And for the other case we have a cost of 155 and we want to find the number of miles associated so we can do this:



Step-by-step explanation:
For this case we can define the following notation:
m= represent the miles travelled
C= represent the cost
Part a
For this case we have the following two points given:

And we want to find a function:

We can find the slope with this formula:

And then we can use the point
to find the intercept
and we got:


So then the linear function is given by:

Part b
For this case we have that m = 475 so we can replace into the function to find the cost like this:

And for the other case we have a cost of 155 and we want to find the number of miles associated so we can do this:


