Final answer:
The simplified form of the expression (x/3 - y/4) / (x/4 + y/3) is (4x - 3y) / (3x + 4y).
Step-by-step explanation:
To simplify the expression (x/3 - y/4) / (x/4 + y/3), we can multiply both the numerator and denominator by the least common multiple of the denominators, which is 12. This gives us ((4x - 3y) / 12) / ((3x + 4y) / 12). Now, we can simplify this further by multiplying the fractions and canceling out any common factors. This gives us (4x - 3y) / (3x + 4y), which corresponds to option A, (4x - 3y) / (3x + 4y).