Freight train is carrying goods across the country. The number of gallons of fuel it has used varies directly with the distance it has traveled. See the graph elow.
1
450 -
400
350
300
250
Number
of gallons
used
200
150
100
50
0
50 100 150 200 250 300 350 400 450
Distance traveled (miles)
(a) How many gallons does the train use per mile?
DO
gallon(s)
Х
$
?
(b) What is the slope of the graph?