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TAGS: Director  Joined: 07 Jan 2018
Posts: 659
Followers: 7

Kudos [?]: 615  , given: 88

If a + b = 20, then (a + b/2) + (b + a/2) = [#permalink]
1
KUDOS 00:00

Question Stats: 60% (01:11) correct 40% (00:29) wrong based on 10 sessions
If a + b = 20, then (a + b/2) + (b + a/2) =

A) 10
B) 20
C) 30
D) 40
E) 50
[Reveal] Spoiler: OA Manager  Joined: 15 Jan 2018
Posts: 147
GMAT 1: Q V
Followers: 3

Kudos [?]: 188  , given: 0

Re: If a + b = 20, then (a + b/2) + (b + a/2) = [#permalink]
1
KUDOS
Notice that if you just add the terms you get a simple question:

(a + b/2) + (b + a/2) = 1.5a + 1.5b = ?

Then you can factor:

1.5a + 1.5b = 1.5(a + b)

and since we know a + b = 20, then 1.5(a + b) = 30
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Need help with GRE math? Check out our ground-breaking books and app. GRE Instructor Joined: 10 Apr 2015
Posts: 2140
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Kudos [?]: 1954  , given: 17

Re: If a + b = 20, then (a + b/2) + (b + a/2) = [#permalink]
1
KUDOS
Expert's post
amorphous wrote:
If a + b = 20, then (a + b/2) + (b + a/2) =

A) 10
B) 20
C) 30
D) 40
E) 50

Here's another approach:

GOAL: find the value of (a + b/2) + (b + a/2)

GIVEN: a + b = 20
Let's take some values of a and b that satisfy the equation a+b = 20, and plug them into our goal expression...

Well, a = 20 and b = 0 satisfy the equation a + b = 20

Now take (a + b/2) + (b + a/2), and replace a and b with 20 and b = 0
We get: (a + b/2) + (b + a/2) = (20 + 0/2) + (0 + 20/2)
= (20 + 0) + (0 + 10)
= 20 + 10
= 30

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com Intern Joined: 17 Feb 2018
Posts: 9
Followers: 0

Kudos [?]: 2 , given: 2

Re: If a + b = 20, then (a + b/2) + (b + a/2) = [#permalink]
SherpaPrep wrote:
Notice that if you just add the terms you get a simple question:

(a + b/2) + (b + a/2) = 1.5a + 1.5b = ?

Then you can factor:

1.5a + 1.5b = 1.5(a + b)

and since we know a + b = 20, then 1.5(a + b) = 30

I just used random numbers to plug in and solve, not sure if it would work in any case however.
Manager  Joined: 26 Jun 2017
Posts: 104
Followers: 0

Kudos [?]: 41 , given: 38

Re: If a + b = 20, then (a + b/2) + (b + a/2) = [#permalink]
the most confident approach is the algebraic one -- the property does not change if you change the sides of the properties because all in all you are adding. So, a+b=20, 20+ a/2+b/2. Then the LCM of the numbers is 2 giving (40+a+b)/2=30
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What you think, you become. Re: If a + b = 20, then (a + b/2) + (b + a/2) =   [#permalink] 05 Mar 2018, 08:26
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