GMAT Changed on April 16th - Read about the latest changes here

 It is currently 24 Apr 2018, 11:17

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If 3a + 2b – 4 = a – b, what is the value of b ?

Author Message
TAGS:

Hide Tags

Senior RC Moderator
Status: It always seems impossible until it's done!!
Joined: 29 Aug 2012
Posts: 1141
Location: India
WE: General Management (Aerospace and Defense)
If 3a + 2b – 4 = a – b, what is the value of b ? [#permalink]

Show Tags

23 Jul 2014, 10:48
1
KUDOS
00:00

Difficulty:

25% (medium)

Question Stats:

74% (00:58) correct 26% (00:49) wrong based on 141 sessions

HideShow timer Statistics

If 3a + 2b – 4 = a – b, what is the value of b ?

(1) 2a^2 = 50

(2) 4a = 20
[Reveal] Spoiler: OA

_________________
Math Expert
Joined: 02 Sep 2009
Posts: 44639
Re: If 3a + 2b – 4 = a – b, what is the value of b ? [#permalink]

Show Tags

23 Jul 2014, 10:53
1
KUDOS
Expert's post
1
This post was
BOOKMARKED
If 3a + 2b – 4 = a – b, what is the value of b ?

3a + 2b – 4 = a – b --> 2a + 3b = 4.

(1) 2a^2 = 50 --> a^2 = 25 --> a = 5 or a = -5. We'll get two different values of b, when substituting these value into 2a + 3b = 4. Not sufficient.

(2) 4a = 20 --> a = 5. We can substitute into 2a + 3b = 4 and get the value of b. Sufficient.

_________________
Director
Joined: 24 Nov 2015
Posts: 576
Location: United States (LA)
Re: If 3a + 2b – 4 = a – b, what is the value of b ? [#permalink]

Show Tags

19 Jul 2016, 14:38
Simplifying question stem 3a + 2b – 4 = a – b , we get 2a + 3b = 4

Statement 1 is 2$$a^2$$ = 50
simplifying $$a^2$$ = 25 , we don't know whether a is positive or negative
a can be 5 or -5 so insufficient

Statement 2 is 4a = 20
clearly we get a = 5 so sufficient
Current Student
Joined: 18 Oct 2014
Posts: 886
Location: United States
GMAT 1: 660 Q49 V31
GPA: 3.98
Re: If 3a + 2b – 4 = a – b, what is the value of b ? [#permalink]

Show Tags

19 Jul 2016, 17:32
Gnpth wrote:
If 3a + 2b – 4 = a – b, what is the value of b ?

(1) 2a^2 = 50

(2) 4a = 20

3a + 2b – 4 = a – b
2a+3b= 4

(1) 2a^2 = 50
'a' can be +5 or -5, and hence it will give different values for 'b'

Not Sufficient.

(2) 4a = 20
a= 5

Sufficient.

Putting the value of a in the equation gives the value of b.

_________________

I welcome critical analysis of my post!! That will help me reach 700+

Current Student
Status: DONE!
Joined: 05 Sep 2016
Posts: 398
Re: If 3a + 2b – 4 = a – b, what is the value of b ? [#permalink]

Show Tags

19 Sep 2016, 08:04
B is correct. Here's why:

(1) 2(a^2) = 50 --> a^2 = 25 --> a = +/- 5

INSUFFICIENT

(2) 4a = 20 --> a = 5

Plug into main equation --> 2(5) + 3b - 4 = 0 --> solve for b

SUFFICIENT
Intern
Joined: 28 Feb 2014
Posts: 8
Re: If 3a + 2b – 4 = a – b, what is the value of b ? [#permalink]

Show Tags

28 Dec 2017, 22:12
Given is 3a + 2b = a - b + 4
2a + 3b = 4. Now value of b is to be calculated
(1) Insufficient: a^2 = 25
a = 5 or -5. Hence, b will have 2 values.

(2) Sufficient: a = 5, hence b = -2.
Re: If 3a + 2b – 4 = a – b, what is the value of b ?   [#permalink] 28 Dec 2017, 22:12
Display posts from previous: Sort by