SOLUTION: Mark's age next year will be three times as old as Kim's age two years ago. If their present ages add to 21, how old is each now?

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Question 545486: Mark's age next year will be three times as old as Kim's age two years ago. If their present ages add to 21, how old is each now?
Answer by oberobic(2304) About Me  (Show Source):
You can put this solution on YOUR website!
M + K = 21
so
M = 21-K
.
Mark's age next year: M+1
Kim's age 2 years ago: K-2
M+1 = 3*(K-2)
.
Substitute M = 21-K.
.
21-K +1 = 3K -6
28 = 4K
K = 7
.
M = 21-7
M = 14
.
Check.
M+1 =15
3(K-2) = 15
Correct.
.
Answer: Mark is 14, and Kim is 7.
.
Done.