Answer:
2.5 gallons
Step-by-step explanation:
Make the denominators of the fractions the same and combine them


Then simplify the fraction

Then subtract how many gallons you have from how many you want

You will need 2.5 gallons to make 3 gallons
<span>Simplifying
3x + -1y = 12
Solving
3x + -1y = 12
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add 'y' to each side of the equation.
3x + -1y + y = 12 + y
Combine like terms: -1y + y = 0
3x + 0 = 12 + y
3x = 12 + y
Divide each side by '3'.
x = 4 + 0.3333333333y
Simplifying
x = 4 + 0.3333333333y</span>
Depends on MPH or Miles Per Hour.
Going 10 mph = 30 minutes
Going 50 mph = 10 minutes
Etc.
I think the answer is D
Hope it helps