SOLUTION: Roberta is 6 times Danielle's age. In 12 years, Roberta will only be 2 times Danielle's age. How old is Danielle now?

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Question 1138903: Roberta is 6 times Danielle's age. In 12 years, Roberta will only be 2 times Danielle's age. How old is Danielle now?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = Roberta's age now
Let +b+ = Danielle's age now
---------------------------------------
(1) +a+=+6b+
(2) +a+%2B+12+=+2%2A%28+b+%2B+12+%29+
----------------------------------
(2) +a+%2B+12+=+2b+%2B+24+
(2) +a+-+2b+=+12+
Plug (1) into (2)
(2) +6b+-+2b+=+12+
(2) +4b+=+12+
(2) +b+=+3+
and
(1) +a+=+6b+
(1) +a+=+6%2A3+
(1) +a+=+18+
-----------------
Danielle is 3 now
check:
(2) +a+%2B+12+=+2%2A%28+b+%2B+12+%29+
(2) +18+%2B+12+=+2%2A%28+3+%2B+12+%29+
(2) +30+=+2%2A15+
(2) +30+=+30+
OK