Guess the age

John was asked how old he is. He said in 2 years I will be twice as old as I was 5 years ago. 
I guessed 12, am I right?

x = John's age now 

x + 2 = 2(x - 5)   {in 2 years, he will be two times what he was 5 years ago}
x + 2 = 2x - 10   {used distributive property}
2 = x - 10   {subtracted x from each side}
x = 12   {added 10 to each side} 

John is 12

- Algebra House