Answer
(a) $C(m)=0.15x+129.50$
(b) 258.5 dollars
(c) 562 miles
Work Step by Step
(a) We can represent the exercise in the form y=mx+b, where m is the rate of change (0.15 dollars per mile) and b is the initial fixed price (129.50 dollars):
$C(m)=0.15x+129.50$
(b) Calculate C(860):
$C(m)=0.15(860)+129.50$
$C(m)=129+129.50$
$C(m)=258.5$ dollars
(c) Replace 213.80 for C(x) and solve for x:
$213.80=0.15x+129.50$
$213.80-129.50=0.15x+129.50-129.50$
$84.3=0.15x$
$84.3/0.15=0.15x0.15$
$x=562$ miles
