Question 1097031
Joan is three times as old as Anne. Fifteen years from now Joan will be twice as old as Anne then what is their ages now? 
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Equations:
J = 3*a
j+15 = 2(a+15)
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Substitute for "j" and solve for "a"::
3a+15 = 2a+30
a = 15 (Anne's age now)
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j = 3a = 3*15 = 45 (Joan's age now)
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Cheers
Stan H.
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