When 3t+4r > 0, comparing (3t+4r)/rt vs (3t+4r)/(r+t) depends on whether rt > r+t or rt < r+t. When 3t+4r < 0, the inequality direction reverses. Test cases: t=1, r=2 gives Col B greater; t=10, r=1 gives Col A greater; t=0.5, r=2 makes them equal. Since different values produce different results, the relationship cannot be uniquely determined.