Question 992329
 Sam is 21 years younger than Angela. 10 years ago, Angela's age was 2 times Sam's age. How old is Sam now? 
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S = A -21
A-10 = 2(S-10)
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Substitute for "S" and solve for "A"::
A - 10 = 2(A-21-10)
A - 10 = 2(A-31)
A - 10 = 2A - 62
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A = 52 yrs (Angela's age now)
S = A-21 = 31 yrs (Sam's age now)
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Cheers,
Stan H.
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