Question 1026548
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Julie is three times as old as her son. In 12 years, Julie's age will be one year less than twice her son's age. How old is Julie now?
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J = 3s,              (1)      (Julie is three times as old as her son.)
J+12 = 2(s+12) - 1.  (2)      (In 12 years, Julie's age will be one year less than twice her son's age.)

Here J = Julie's age now, s = Julie' son age now.

Substitute J = 3s from (1) into (2). You will get single equation for s:

3s + 12 = 2(s+12) - 1,   or

3s + 12 = 2s + 24 - 1,   or

s = 24 - 1 - 12 = 11.

Thus Julie' son is 11 years now. 
Then Julie is 3*s = 33 years old now.

Solved.
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