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# If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithm

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Director
Joined: 07 Jan 2018
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Kudos [?]: 602 [0], given: 88

If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithm [#permalink]  10 Jan 2019, 06:40
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0% (00:00) correct 100% (01:57) wrong based on 2 sessions
If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithmetic mean) of a and b ?

A) 0.1

B) 0.5

C) 1

D) 2.5

E) 5
[Reveal] Spoiler: OA
Intern
Joined: 07 Jan 2019
Posts: 38
Followers: 0

Kudos [?]: 20 [0], given: 11

Re: If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithm [#permalink]  10 Jan 2019, 09:20
Add 12a+3b= 1 and 7b-2a=9, then we will get 10a+10b=10 which results 10(a+b)=10. Thus a+b=1.
therefore, Arithmetic mean of a and b = a+b/2 =1/2 = 0.5

Thank You.
GRE Instructor
Joined: 10 Apr 2015
Posts: 1995
Followers: 60

Kudos [?]: 1811 [0], given: 9

Re: If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithm [#permalink]  10 Jan 2019, 09:53
Expert's post
ARIJOSHI wrote:
Thank You.

Perfect solution!

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com

Re: If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithm   [#permalink] 10 Jan 2019, 09:53
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