GRE Sample Test 2 Quantitative Reasoning 1

There are variables in the answer choices, so Plug In. If r = 2, then 4((2) − s) = −2.
Divide both sides by 4 to find 2 − s = −0.5. So, s = 2.5. The target answer is r, which is 2. Go to the answer choices and Plug In 2.5 for s. Choice (B) is the only answer choice that matches your target of 2.