Linear Equation

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crackgmat007: Legendary Member; Posts: 882; Joined: Fri Feb 20, 2009 2:57 pm; Thanked: 15 times; Followed by:1 members; GMAT Score:690

Linear Equation

by crackgmat007 » Tue May 05, 2009 9:37 am

E. If x, y, and k are positive numbers such that (x/ y+x) * (10) + (y/x+y) * (20) = k and if x < y, which of the following could be the value of k?
A. 10
B. 12
C. 15
D. 18
E. 30

OA - D

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Source: Beat The GMAT — Problem Solving | Tue May 05, 2009 9:37 am

dtweah: Master | Next Rank: 500 Posts; Posts: 487; Joined: Fri Mar 27, 2009 5:49 am; Thanked: 36 times

Re: Linear Equation

by dtweah » Tue May 05, 2009 10:05 am

crackgmat007 wrote:E. If x, y, and k are positive numbers such that (x/ y+x) * (10) + (y/x+y) * (20) = k and if x < y, which of the following could be the value of k?
A. 10
B. 12
C. 15
D. 18
E. 30

OA - D

k=10(x+2Y)/x+y
The only values of x and y that cancel the 10 is 2 and 8.

This gives D answer.

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dtweah: Master | Next Rank: 500 Posts; Posts: 487; Joined: Fri Mar 27, 2009 5:49 am; Thanked: 36 times

Re: Linear Equation

by dtweah » Tue May 05, 2009 10:07 am

crackgmat007 wrote:E. If x, y, and k are positive numbers such that (x/ y+x) * (10) + (y/x+y) * (20) = k and if x < y, which of the following could be the value of k?
A. 10
B. 12
C. 15
D. 18
E. 30

OA - D

K=10 (x+2y)/x+y

2+8 cancel the 10.
So D.

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