homogeneous solution

Problem
In a class experiment, a student needs 5 liters of 6% solution. He found a 4% and a 10% solution in the laboratory. How many liters of each solution should he mix in order to obtain 5 liters of 6% solution?
A. 3.33 liters of 4% and 1.67 liters of 10% solution
B. 1.67 liters of 4% and 3.33 liters of 10% solution
C. 3.67 liters of 4% and 1.33 liters of 10% solution
D. 1.33 liters of 4% and 3.67 liters of 10% solution