GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 19 Oct 2019, 23:33

### 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

# What is the value of b – 2c ?

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 58445
What is the value of b – 2c ?  [#permalink]

### Show Tags

23 Jun 2017, 08:27
00:00

Difficulty:

25% (medium)

Question Stats:

79% (01:33) correct 21% (01:38) wrong based on 80 sessions

### HideShow timer Statistics

What is the value of $$b – 2c$$?

(1) $$ab – 2cd + bd – 2ac = 8$$

(2) $$a = 4 – d$$

_________________
Intern
Joined: 18 Aug 2013
Posts: 3
Re: What is the value of b – 2c ?  [#permalink]

### Show Tags

23 Jun 2017, 11:49
2
Bunuel wrote:
What is the value of $$b – 2c$$?

(1) $$ab – 2cd + bd – 2ac = 8$$

(2) $$a = 4 – d$$

The best way to do this sort of problem is usually to try to isolate what we're being asked to solve for.

Statement 1:

$$ab - 2cd + bd - 2ac = 8$$

Let's try get all the "b" terms together and all the "2c" terms together:

$$ab + bd - 2ac - 2cd = 8$$

Now we can factor out the b in the first two terms and a negative 2c in the second two terms (be careful to change the signs properly):

$$b(a + d) -2c (a + d) = 8$$

Finally, we can divide by (a+d):

$$b - 2c = \frac{8}{a+d}$$

At this point, we're stuck. We can't solve for $$b-2c$$ without knowing the value of $$a+d$$
Insufficient.

Statement 2:
Statement 2 doesn't give us any information about b or about c.
Insufficient.

Combined:
We can rewrite Statement 2 as:

$$a+d = 4$$

Now we can substitute in our rewritten first equation:

$$b - 2c = \frac{8}{4}$$

$$b - 2c = 2$$
Sufficient.

C.
Manager
Joined: 05 Nov 2014
Posts: 102
Location: India
Concentration: Strategy, Operations
GMAT 1: 580 Q49 V21
GPA: 3.75
Re: What is the value of b – 2c ?  [#permalink]

### Show Tags

24 Jun 2017, 06:06
What is the value of b–2cb–2c?

(1) ab–2cd+bd–2ac=8ab–2cd+bd–2ac=8

(2) a=4–d

Solution:

Statement 1: Rearranging,
we get a(b-2c)+ d(b-2c)=8
Taking out the common factor, (b-2c) (a+d)=8.
We can't find the unique value of either of terms as infinite values are possible.

Statement 2: Insufficient on its own.

Combining St1 and St2,
We get a unique value of b-2c. We get 4 as the value.
Therefore, the answer is Option C.
Director
Joined: 09 Mar 2018
Posts: 994
Location: India
Re: What is the value of b – 2c ?  [#permalink]

### Show Tags

19 Feb 2019, 01:08
Bunuel wrote:
What is the value of $$b – 2c$$?

(1) $$ab – 2cd + bd – 2ac = 8$$

(2) $$a = 4 – d$$

After manipulating both options A and B, combining we get

b(a+d) -2c (a+d) = 8

b-2c (a+d) = 8

from 2) a+d = 4

b-2c = 2

C
_________________
If you notice any discrepancy in my reasoning, please let me know. Lets improve together.

Quote which i can relate to.
Many of life's failures happen with people who do not realize how close they were to success when they gave up.
Re: What is the value of b – 2c ?   [#permalink] 19 Feb 2019, 01:08
Display posts from previous: Sort by

# What is the value of b – 2c ?

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne