SOLUTION: If 3x + y = a and 4x – y = b, then determine the value of y in terms of a and b.

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Question 254848: If 3x + y = a and 4x – y = b, then determine the value of y in terms of a and b.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
3x+%2B+y+=+a
4x-y+=+b
Solve for x in eq. 1 and substitute into eq. 2,
3x+%2B+y+=+a
3x++=+a-y
x=%281%2F3%29%28a-y%29
4x=%284%2F3%29%28a-y%29
Now substitute,
4x-y+=+b
%284%2F3%29%28a-y%29-y+=+b
4%28a-y%29-3y+=+3b
4a-4y-3y=3b
-7y=3b-4a
y=%281%2F7%29%284a-3b%29