SOLUTION: Karen is twice as old as Lori. Three years from now, the sum of their ages will be 42. How old is Karen?

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Question 1133388: Karen is twice as old as Lori. Three years from now, the sum of their ages will be 42. How old is Karen?
Found 2 solutions by math_helper, MathTherapy:
Answer by math_helper(2461) (Show Source):
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L = Lori's age
K = Karen's age

1. K = 2L 2. (K+3) + (L+3) = 42

Re-writing (2) w/substitution for L (L=(1/2)K):

2'. (K+3) + ((1/2)K+3) = 42 (3/2)K = 36 K = (2/3)(36) = 24

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Ans:
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Check:
K=24 --> L=12
In three years: 24+3 + 12+3 = 27 + 15 = 42 (ok)

Answer by MathTherapy(10552) (Show Source):
You can put this solution on YOUR website!

Karen is twice as old as Lori. Three years from now, the sum of their ages will be 42. How old is Karen?

Let Karen's and Lori's ages be K, and L, respectively
Then we get: K = 2L ------- eq (i)
Also, K + 3 + L + 3 = 42 =====> K + L = 36 ======> L = 36 - K ------- eq (ii)
K = 2(36 - K) ------ Substituting 36 - K for L in eq (i)
K = 72 - 2K
K + 2K = 72
3K = 72
K, or Karen is: