SOLUTION: Ray is 3 times as old as his brother how old is he if in 7 years he will be double his brother's age?

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Question 903242: Ray is 3 times as old as his brother how old is he if in 7 years he will be double his brother's age?
Found 2 solutions by lwsshak3, josmiceli:
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Ray is 3 times as old as his brother how old is he if in 7 years he will be double his brother's age?
***
let x=brother's age
3x=Ray's age
..
In 7 yrs:
x+7=brother's age
3x+7=Ray's age
3x+7=2(x+7)
3x+7=2x+14
x=7
3x=21
Ray's age=21

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +r+ = Ray's age now
Let +b+ = his brother's age now
---------------
(1) +r+=+3b+
(2) +r+%2B+7+=+2%2A%28+b+%2B+7+%29+
-------------------------
(2) +r+%2B+7+=+2b+%2B+14+
(2) +r+=+2b+%2B+7+
Substitute (1) into (2)
(2) +3b+=+2b+%2B+7+
(2) +b+=+7+
and
(1) +r+=+3b+
(1) +r+=+3%2A7+
(1) +r+=+21+
----------------
Ray is 21
His brother is 7
----------------
check:
(2) +r+%2B+7+=+2b+%2B+14+
(2) +21+%2B+7+=+2%2A7+%2B+14+
(2) +28+=+14+%2B+14+
(2) +28+=+28+
OK