Answer
.25 per mile, daily fee of $32
Work Step by Step
4 day trip, 450 miles = 240.50
3 day trip, 200 miles = 146
$4x+450y=240.50$
$3x+200y=146$
$4x+450y=240.50$
$-3(4x+450y=240.50)$
$-12x-1350y=-721.5$
$3x+200y=146$
$4*(3x+200y=146)$
$12x+800y=584$
$-12x-1350y=-721.5$
$12x+800y=584$
$12x+800y+(-12x-1350y)=584-721.5$
$12x-12x+800y-1350y=-137.5$
$-550y=-137.5$
$-550y/-550=-137.5/-550$
$y=.25$
$3x+200y=146$
$3x+200*.25=146$
$3x+50=146$
$3x=96$
$3x/3=96/3$
$x=32$