It is in standard form: y=mx+b
"Sum" tells us it's an addition problem:
One term is 12 and the other is 9/x
SO
The expression is:
12+9/x
The answer is C. Explanation: The line isn’t a straight line, so it can’t be a linear line. Then, do the vertical line test to see if the line is a function (to do this, draw a vertical line through the graph, and see if it passes more than one point on the graph. If the vertical line passes any more than one point on the graph on any spot, it is not a function), and since the graph fails the vertical line test, it is not a function. Therefore, the answer is C.
$291-$210=$81
$81/0.15= 540 miles
I believe the answer is 540 mi.