Target question: What is the value of x-y?VJesus12 wrote:If x and y are positive, what is the value of x-y?
$$(1)\ \ (x^2-y^2)/(x+y)=4$$
$$(2)\ \ x+y=7$$
Given: x and y are positive
Statement 1: (x² - y²)/(x + y) = 4
Factor the numerator to get: (x - y)(x + y)/(x + y) = 4
Simplify: (x - y) = 4 PERFECT!
Since we can answer the target question with certainty, statement 1 is SUFFICIENT
Statement 2: x + y = 7
There are several values of x and y that satisfy statement 2. Here are two:
Case a: x = 6 and y = 1, in which case x - y = 6 - 1 = 5
Case b: x = 5 and y = 2, in which case x - y = 5 - 2 = 3
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT
Answer: A
Cheers,
Brent
