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Moderator  Joined: 18 Apr 2015
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If a-b/a+b =2 and b=1, what is the value of a ? [#permalink]
Expert's post 00:00

Question Stats: 100% (00:24) correct 0% (00:00) wrong based on 4 sessions

If $$\frac{a-b}{a+b} = 2$$ and $$b=1$$, what is the value of a ?

A) 1

B) 0

C) -1

D) -2

E) -3
[Reveal] Spoiler: OA

_________________ GRE Prep Club Legend  Joined: 07 Jun 2014
Posts: 4857
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
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Re: If a-b/a+b =2 and b=1, what is the value of a ? [#permalink]
1
KUDOS
Expert's post
Explanation

Here we have the expression $$\frac{a-b}{a+b} = 2$$ and also given that $$b=1$$.

Putting value of b in the expression.

$$\frac{a-b}{a+b} = 2$$

or $$\frac{a-1}{a+1} = 2$$ or $$a-1 = 2a + 2$$ or $$a = -3$$.

Hence E is the correct option.
_________________

Sandy
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Re: If a-b/a+b =2 and b=1, what is the value of a ? [#permalink]
1
KUDOS
Expert's post
Carcass wrote:

If $$\frac{a - b}{a + b} = 2$$ and $$b = 1$$, what is the value of a ?

A) 1

B) 0

C) -1

D) -2

E) -3

If b = 1, let's first replace b with 1 to get: (a - 1)/(a + 1) = 2
Multiply both sides of the equation by (a+1) to get: a - 1 = 2(a + 1)
Simplify: a - 1 = 2a + 2
Subtract a from both sides: -1 = a + 2
Subtract 2 from both sides: -3 = a

[Reveal] Spoiler:
E

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com Sign up for our free GRE Question of the Day emails

Moderator  Joined: 18 Apr 2015
Posts: 5845
Followers: 94

Kudos [?]: 1144 , given: 5448

Re: If a-b/a+b [#permalink]
Expert's post
Explanation

Whenever you see such question the fastest way is to plug in the answer choices. Start almost always from the bottom, which means E

$$\frac{-3-1}{-3+1}= \frac{-4}{-2}=2$$

E wins
_________________ Re: If a-b/a+b   [#permalink] 22 Nov 2017, 11:27
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