SOLUTION: b + a 1 _______ = ___ ab f solve for b. this is a proportion b+a over ab equals 1 over f. after cross product i dont know how to get the b by it's self.

Algebra ->  Proportions  -> Lessons -> SOLUTION: b + a 1 _______ = ___ ab f solve for b. this is a proportion b+a over ab equals 1 over f. after cross product i dont know how to get the b by it's self.       Log On


   

Question 21437: b + a 1
_______ = ___

ab f
solve for b.
this is a proportion b+a over ab equals 1 over f.
after cross product i dont know how to get the b by it's self. I have been given the answer but dont know how to get there...
the answer is b= fa over a-f
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Solve for b:
%28b%2Ba%29%2Fab+=+1%2Ff Multiply both sides by ab.
a%2Bb+=+ab%2Ff Multiply both sides by f.
af+%2B+bf+=+ab Subtract bf from both sides.
af+=+ab+-+bf Factor b from the right side.
af+=+b%28a-f%29 Divide both sides by (a-f).
af%2F%28a-f%29+=+b or fa%2F%28a-f%29