SOLUTION: Alfred is three times as old as his brother.Six years ago, the sum of their ages was equal to Alfred's present age.How old are they now?thank you!

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Question 566620: Alfred is three times as old as his brother.Six years ago, the sum of their ages was equal to Alfred's present age.How old are they now?thank you!
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = Alfred's age now
+a+-+6+ = Alfred's age 6 yrs ago
Let +b+ = his brother's age now
+b+-+6+ = brother's age 6 yrs ago
--------------------------------------
given:
(1) +a+=+3b+
(2) +%28+a+-+6+%29+%2B+%28+b+-+6+%29+=+a+
--------------------------------------
(2) +a+%2B+b+-+12+=+a+
Subtract +a+ from both sides
(2) +b+-+12+=+0+
(2) +b+=+12+
and
(1) +a+=+3b+
(1) +a+=+36+
Alfred is 36 now, and
his brother is 12 now