Answer
$23 per day, .21 per mile
Work Step by Step
5 day trip, 300 miles = 178
4 day trip, 500 miles = 197
$5x+300y=178$
$4x+500y=197$
$5x+300y=178$
$-4*(5x+300y=178)$
$-20x-1200y=-712$
$4x+500y=197$
$5*(4x+500y=197)$
$20x+2500y=985$
$-20x-1200y=-712$
$20x+2500y=985$
$20x+2500y+(-20x-1200y)=985-712$
$20x-20x+2500y-1200y=273$
$1300y=273$
$1300y/1300=273/1300$
$y=.21$
$5x+300y=178$
$5x+300*.21=178$
$5x+63=178$
$5x=115$
$5x/5=115/5$
$x=23$
