Question 2637
Lets assume -
Denise = X and Earl  = Y

 X+Y=42 (Sum of their ages is 42)
-X+Y=-8 (This is actually Y+8=X which is translated from Earl is 8 years younger than Denise)
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2Y=34
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Y = 17
X = 42-17 = 25

So Earl is 17 and Denise is 25 !!