Solve the proportion. 5/7 = 10/x+6

5/7 = 10/x + 6

5/7 = (10+ 6x)/x

5x = 7(10+6x)

5x = 70+42x

5x - 42x = 70

-37x = 70

x = -70/37

My best guess would be that the independent variable is A. the amount of miles Larry drives.
An independent variable is one that isn't changed by the other variables you are trying to measure.
The amount of miles Larry drives doesn’t depend on anything in this situation.
The question only mentions gallons of gas and miles so I would think you disregard the type of roads Larry drives on and type of car Larry drives.
The amount of gasoline Larry uses is a dependent variable because it depends on the amount of miles Larry drives.
Hope this helps