# When n liters of fuel was added to a tank that was already 1/3 full…

# Solution:

We can let c = the capacity of the tank. Since when n liters of fuel was added to a tank that was already 1/3 full, the tank was filled to 7/9 of its capacity, we can say:

n + (1/3)c =(7/9)c

Multiplying the equation by 9 we have:

9n + 3c = 7c

9n = 4c

c = (9/4)n

**Answer: D**

#### About The Author

Scott Woodbury-Stewart is the founder & CEO of Target Test Prep. A passionate teacher who is deeply invested in the success of his students, Scott began his career teaching physics, chemistry, math, and biology. Since then, he has spent more than a decade helping students gain entry into the world’s top business schools, logging 10,000+ hours of GMAT instruction. Scott also served as lead content developer and curriculum architect for the revolutionary quant course Target Test Prep GMAT Quant.