Final answer:
The slope of the linear function is $1.75 per mile and the y-intercept is $50.
The equation C(x) = $50 + $1.75x
Step-by-step explanation:
The linear function, C(x), is given by the equation C(x) = $50 + $1.75x, where x is the number of miles driven. 
The slope of the linear function is $1.75 per mile. 
The units for the slope are dollars per mile. 
The y-intercept of the linear function is $50. 
The units for the y-intercept are dollars.