SOLUTION: Kevin is five years older than his younger brother Jack. Their cousin Michael is three times as old as Kevin. Together, the sum of Jack, Kevin, and Michael's ages is 40. How old is

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Question 1053195: Kevin is five years older than his younger brother Jack. Their cousin Michael is three times as old as Kevin. Together, the sum of Jack, Kevin, and Michael's ages is 40. How old is Jack?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
(1) +k+=+j+%2B+5+
(2) +m+=+3k+
(3) +k+%2B+j+%2B+m+=+40+
------------------------
(1) +j+=+k+-+5+
Substitute (1) and (2) into (3)
(3) +k+%2B+k+-+5+%2B+3k+=+40+
(3) +5k+-+5+=+40+
(3) +5k+=+45+
(3) +k+=+9+
and
(1) +j+=+k+-+5+
(1) +j+=+9+-+5+
(1) +j+=+4+
and
(2) +m+=+3k+
(2) +m+=+3%2A9+
(2) +m+=+27+
--------------------
Kevin is 9
Jack is 4
Mike is 27
--------------
check:
(1) +k+=+j+%2B+5+
(1) +9+=+4+%2B+5+
(1) +9+=+9+
OK
You can check (2) and (3)