SOLUTION: can you show the steps of solving this problem by cross multiplying (7-2n)/(7+2n)=1/18

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Question 297349: can you show the steps of solving this problem by cross multiplying (7-2n)/(7+2n)=1/18
Found 2 solutions by jim_thompson5910, richwmiller:
Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
Start with the given equation.


Cross multiply


Distribute.


Subtract from both sides.


Subtract from both sides.


Combine like terms on the left side.


Combine like terms on the right side.


Divide both sides by to isolate .


Reduce.


----------------------------------------------------------------------

Answer:

So the solution is which approximates to .
Answer by richwmiller(17219)   (Show Source): You can put this solution on YOUR website!
This is one reason that many teachers don't like "cross multiplying"
Cross multiplying is a short cut to this
Multiply both sides by 7+2n
Multiply both sides by 18
In cross multiplying you just remove the denominators and multiply the opposite numerator by the denominator
a/b=c/d
multiply c*b and a*d
Multiply the numerator on one side by the denominator on the other side.
Do it again with the other side.
So in the end you should have
(7-2n)*18 = 1*(7+2n)
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