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# 10y + 17z = ?

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Manager
Joined: 07 Jun 2017
Posts: 174
Location: India
Concentration: Technology, General Management
GMAT 1: 660 Q46 V38
GPA: 3.6
WE: Information Technology (Computer Software)
10y + 17z = ?  [#permalink]

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22 Oct 2017, 22:41
00:00

Difficulty:

15% (low)

Question Stats:

96% (01:16) correct 4% (01:46) wrong based on 48 sessions

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10y + 17z = ?

(1) x + 2y + 7z = 40

(2) 2x-­ 6y ­- 3z = 30

_________________

Regards,
Naveen
email: nkmungila@gmail.com
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Manager
Joined: 15 Aug 2016
Posts: 128
10y + 17z = ?  [#permalink]

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23 Oct 2017, 01:09
(1) x + 2y + 7z = 40

We dont know the value of x or Y or Z. Insuff

(2) 2x-­ 6y ­- 3z = 30

We dont know the value of x or Y or Z. Insuff

(1) and (2)

Multiplying (1) by 2 and then subtracting (2) from it
=> 2x+4y+14z-(2x-6y-3z)=80-30
=>2x-2x+4y+6y+14z+3z=50
=> 10y+17z=50
Suff.
Ans=C
Intern
Joined: 15 May 2017
Posts: 33
GMAT 1: 770 Q51 V45
Re: 10y + 17z = ?  [#permalink]

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23 Oct 2017, 14:42
nkmungila wrote:
10y + 17z = ?

(1) x + 2y + 7z = 40

(2) 2x-­ 6y ­- 3z = 30

For all DS problems note exactly what the question is asking for, in this case 10y + 17z, and search proactively for the fastest route to exactly that value.

(1) includes three variables and cannot be manipulated to isolate 10y + 17z.

(2) also includes three variables that cannot be manipulated to isolate 10y + 17z.

When there are simultaneous equations visually stack them on your scratch worksheet as such:

x + 2y + 7z = 40
2x - 6y - 3z = 30

Note that by multiplying the entire equation in (1) by 2 it becomes possible to stack and solve the equations to eliminate the entire x variable such that:

2x + 4y + 14z = 80
-(2x - 6y - 3z = 30)
10y + 17z = 50

Therefore the statements combined are sufficient and choice C is the correct answer.
_________________

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Re: 10y + 17z = ? &nbs [#permalink] 23 Oct 2017, 14:42
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