Question 29980
let W represent the age of mr Williams
let S represent the age of mr Williams' son

Currently, mr williams is three times as old as his son: this becomes,

W = 3S
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Twelve years from now, he will be only twice as old as his son. This becomes,

W + 12 = 2x(S + 12)
W + 12 = 2S + 24
W = 2S + 12
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We now substitute for W = 3S into the above eqn,

3S = 2S + 12
S = 12
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W = 36
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