Problem Solving (PS) | Re: If x - y = 5 and (x + 1)(y - 1) = 5, what is the value of xy?

Given: (x + 1)(y - 1) =5
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
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