If x - y = 5 and (x + 1)(y - 1) = 5, what is the value of xy?
(A) -1
(B) 1
(C) 5
(D) 10
(E) 11
Answer: E
Source: www.gmatprepnow.com
If x - y = 5 and (x + 1)(y - 1) = 5, what is the value of xy?
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Given: (x + 1)(y - 1) = 5Brent@GMATPrepNow wrote: ↑Sat Jul 02, 2022 5:28 amIf x - y = 5 and (x + 1)(y - 1) = 5, what is the value of xy?
(A) -1
(B) 1
(C) 5
(D) 10
(E) 11
Answer: E
Source: www.gmatprepnow.com
Expand and simplify the left side: xy - x + y - 1 = 5
Add 1 to both sides of the equation: xy - x + y = 6
Add x and subtract y from both sides: xy = 6 + x - y
Substitute: xy = 6 + 5
Simplify: xy = 11
Answer: E