SAT Math Multiple Choice Practice Question 142: Answer and Explanation
10. Let x~y be defined as . For what value of x does x~3 = x?
Correct Answer: D
D. Substituting 3 for y gives you . You want this equation to equal x, so . Multiplying both sides by 2 gives you x + 3 = 2x, and subtracting x from each side gives you x = 3. As always, if you aren't in the mood to do algebra, you can find this answer by plugging in answer choices until you find one that works.