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If = 7/x + 2/y = 7 and xy = 4, then 7y + 2x =? A. 28 B. 14 C. 7/4 D. 4

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If = 7/x + 2/y = 7 and xy = 4, then 7y + 2x =? A. 28 B. 14 C. 7/4 D. 4  [#permalink]

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New post 31 Mar 2019, 08:28
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Question Stats:

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If \(= \frac{7}{x} + \frac{2}{y} = 7\) and \(xy = 4\), then \(7y + 2x =?\)

A. 28

B. 14

C. \(\frac{7}{4}\)

D. \(\frac{4}{7}\)

E. \(\frac{2}{7}\)

Source: McGraw-Hill's GMAT

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If = 7/x + 2/y = 7 and xy = 4, then 7y + 2x =? A. 28 B. 14 C. 7/4 D. 4  [#permalink]

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New post 31 Mar 2019, 08:52
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Top Contributor
SajjadAhmad wrote:
If \(\frac{7}{x} + \frac{2}{y} = 7\) and \(xy = 4\), then \(7y + 2x =?\)

A. 28

B. 14

C. \(\frac{7}{4}\)

D. \(\frac{4}{7}\)

E. \(\frac{2}{7}\)

Source: McGraw-Hill's GMAT


Given: \(\frac{7}{x} + \frac{2}{y} = 7\)

Multiply both sides by x to get: \(7 + \frac{2x}{y} = 7x\)

Multiply both sides by y to get: \(7y + 2x = 7xy\)

Since we're told that xy = 4, we can take the above equation and replace xy with 4 to get: \(7y + 2x = 7(4)\)

Simplify: \(7y + 2x = 28\)

Answer: A

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Brent
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Re: If = 7/x + 2/y = 7 and xy = 4, then 7y + 2x =? A. 28 B. 14 C. 7/4 D. 4  [#permalink]

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New post 31 Mar 2019, 10:17
SajjadAhmad wrote:
If \(= \frac{7}{x} + \frac{2}{y} = 7\) and \(xy = 4\), then \(7y + 2x =?\)

A. 28

B. 14

C. \(\frac{7}{4}\)

D. \(\frac{4}{7}\)

E. \(\frac{2}{7}\)

Source: McGraw-Hill's GMAT


SajjadAhmad i think this question should be tagged sub 600 level
solve the eqn
m]= \frac{7}{x} + \frac{2}{y} = 7[/m]
7y+2x=7xy
xy=4 given
so 7x+2y= 28
IMO A
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Re: If = 7/x + 2/y = 7 and xy = 4, then 7y + 2x =? A. 28 B. 14 C. 7/4 D. 4  [#permalink]

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New post 31 Mar 2019, 10:23
Don't worry dear, after approx 30 timers attempts GMAT Club timer's system automatically manage its difficulty level.

Thanks


Archit3110 wrote:
SajjadAhmad wrote:
If \(= \frac{7}{x} + \frac{2}{y} = 7\) and \(xy = 4\), then \(7y + 2x =?\)

A. 28

B. 14

C. \(\frac{7}{4}\)

D. \(\frac{4}{7}\)

E. \(\frac{2}{7}\)

Source: McGraw-Hill's GMAT


SajjadAhmad i think this question should be tagged sub 600 level
solve the eqn
m]= \frac{7}{x} + \frac{2}{y} = 7[/m]
7y+2x=7xy
xy=4 given
so 7x+2y= 28
IMO A

_________________
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Joined: 18 Aug 2017
Posts: 3008
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Re: If = 7/x + 2/y = 7 and xy = 4, then 7y + 2x =? A. 28 B. 14 C. 7/4 D. 4  [#permalink]

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New post 31 Mar 2019, 10:25
SajjadAhmad wrote:
Don't worry dear, after approx 30 timers attempts GMAT Club timer's system automatically manage its difficulty level.

Thanks


Archit3110 wrote:
SajjadAhmad wrote:
If \(= \frac{7}{x} + \frac{2}{y} = 7\) and \(xy = 4\), then \(7y + 2x =?\)

A. 28

B. 14

C. \(\frac{7}{4}\)

D. \(\frac{4}{7}\)

E. \(\frac{2}{7}\)

Source: McGraw-Hill's GMAT


SajjadAhmad i think this question should be tagged sub 600 level
solve the eqn
m]= \frac{7}{x} + \frac{2}{y} = 7[/m]
7y+2x=7xy
xy=4 given
so 7x+2y= 28
IMO A



ohh well thats a fun fact I wasnt aware of this... thanks for sharing.. :)
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Re: If = 7/x + 2/y = 7 and xy = 4, then 7y + 2x =? A. 28 B. 14 C. 7/4 D. 4   [#permalink] 31 Mar 2019, 10:25
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If = 7/x + 2/y = 7 and xy = 4, then 7y + 2x =? A. 28 B. 14 C. 7/4 D. 4

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