If 10 gallons of grape juice are added to 40 gallons of a mixture, which contains 10 percent grape juice then what percent of the resulting mixture is grape juice?	Pick one.
A) 14 % B) 25 % C) 28 % D) 34 % E) 50 %

Rationale: "mixture contains 4 gallons of grape juice out of 40 gallons after addition : 14 gallons of grape juice out of 50 gallons = = > 28 % answer c"
Answer: C