SOLUTION: Alfred is twice as old as his brother. Four years ago he was four times as old. How old is Alfred now?

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Question 182721: Alfred is twice as old as his brother. Four years ago he was four times as old. How old is Alfred now?
Found 2 solutions by vleith, Mathtut:
Answer by vleith(2517) About Me  (Show Source):
You can put this solution on YOUR website!
Alfred+=+2+%2A+Brother
Alfred+-+4+=+4+%2A+%28Brother-4%29
A+=+2B
A-4+=+4B+-+16
2B+-+4+=+4B+-+16
12+=+2B
6+=+B
Brother is 6.
Alfred is 2*6 = 12

Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
Alfred is twice as old as his brother. Four years ago he was four times as old. How old is Alfred now?
:
lets call the ages of alfred and brother, a and b , respectively
:
a=2b.......eq 1
a-4=4(b-4).eq 2
:
take a's value of 2b from eq 1 and plug it into eq 2
:
2b-4=4(b-4)
:
2b-4=4b-16
:
2b=12
:
highlight%28b=6%29age of brother
:
highlight%28a=2%286%29=12%29age of alfred