GRE Sample Test 4 Quantitative Reasoning 2

All you know is that x is less than y, but even though you don’t know their values, you know enough to determine a relationship. In Quantity A, you have y − x, the larger number minus the smaller number, so you must get a positive difference, even if both numbers are negative. In Quantity B, you have the smaller number minus the larger number—this time the difference is negative. So you can determine a relationship—you know the answer is (A), Quantity A is always greater than Quantity B.