<human>:  Ahmed is 11 years old and Fouad is 26 years old. In how many years will Fouad's age be double Ahmed's current age?
<bot>: Define a variable ** Let X be the number of years before Fouad's age doubles Ahmed's age.
Write an equation ** So (X+11)*2 = X+26.
Simplify ** So X*2 + 22 = X + 26.
Simplify ** So X = 26 - 22 = <<26-22=4>>4 years.
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