Age Problem

Lyle's current age is 23 years.  Melanie's current age is 15 years.  How many years ago was Lyle's age twice Melanie's age?
A.)  16
B.)  9
C.)  8
D.)  7
E.)  5

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23 = Lyle's current age
15 = Melanie's current age   {Melanie is currently 8 years younger than Lyle}

23 - x = 2(15 - x)   {Lyle was twice as old as Melanie -x years ago}
23 - x = 30 - 2x   {used distributive property}
-7 - x = -2x   {subtracted 23 from each side}
-x = 7   {added x to each side}

Lyle was twice as old as Melanie 7 years ago

D.)  7

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