Fraction word problem

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.
magellan333
Posts: 4
Joined: Sun Jan 05, 2014 4:09 am
Contact:

Fraction word problem

I have worked this a few times and keep ending up with 45/7 for the answer. The book says -9 is the answer. Any help is appreciated!

When a certain number is added to the numerator and subtracted from the denominator of the fraction 3/8, the result is 6. What is the number?

I have tried the following :

3+x/8-x = 6

(8-x) 3+x/8-x = 6 (8-X)

3+X = 48-6x

45=7x

X=45/7

stapel_eliz
Posts: 1628
Joined: Mon Dec 08, 2008 4:22 pm
Contact:
I have worked this a few times and keep ending up with 45/7 for the answer. The book says -9 is the answer. Any help is appreciated!

When a certain number is added to the numerator and subtracted from the denominator of the fraction 3/8, the result is 6. What is the number?

I have tried the following :

3+x/8-x = 6
(8-x) 3+x/8-x = 6 (8-X)
3+X = 48-6x
45=7x
X=45/7
Your set-up and steps look find, so let's check the book's answer:

. . . . .$\frac{3\, +\, (-9)}{8\, -\, (-9)}$

. . . . .$\frac{3\, -\, 9}{8\, +\, 9}$

. . . . .$\frac{-6}{17}$

...which clearly doesn't equal 6. Now that we've established that the book is wrong, check your answer to see if you (can prove that you) are correct.