GRE Sample Test 4 Quantitative Reasoning 2

Notice the way the diagram is set up: a + b is the same as PQ. The equation is 8a + 8b = 24. Divide both sides by 8. You end up with a + b = 3. PQ is 3 and because 3 is greater than 2, the answer is (A). Note that you did not have to solve for a or b individually.