I'm making a graph, but I can't tell which is the independent or dependent variable?

Question

they are "dollars spent" and "gallons bought". which one depends on the other?

Answer 1

the "gallons bought" is the dependent variable. the "dollars spent" is the independent variable.

Answer 2

It really could be either, if you had five dollars, and spend it on gasoline, the money would be the indep variable, and gallons the dependent. But the usual case is we are filling a tank, so gallons is the indep variable, and money the dependent.

Answer 3

thanks