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How many drinks?

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Intern
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Joined: 26 Dec 2016
Posts: 29
How many drinks?  [#permalink]

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New post 17 Jan 2018, 14:23
1
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

60% (00:51) correct 40% (00:00) wrong based on 5 sessions

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Jim spent $60 purchasing lattes and coffees for his coworkers. If lattes cost $6 and coffees cost $3, and Jim purchased two more coffees than lattes, how many total drinks did he purchase?

A) 6
B) 8
C) 10
D) 12
E) 14

Official Solution:

In setting up a word problem like this, be sure to use meaningful variables. Here your variables are lattes (which you can call L) and coffees (which you can call C).

You can set up an equation to account for the $60 total: $6 times the number of lattes plus $3 times the number of coffees will account for the $60, so 6L + 3C = 60. You can then simplify by dividing everything by 3: 2L + C = 20.

You can also set up an equation based on the fact that there were 2 more coffees than lattes. The number of coffees, C, is equal to 2 plus the number of lattes, L, so:

C = 2 + L

With two equations and two variables, you can now solve. A quick way to do that is to subtract L from both sides of the second equation:

C - L = 2

If you then multiply both sides by 2, you have:

2C - 2L = 4


Which sets up for the elimination method when you stack and add the two equations:

2C - 2L = 4
C + 2L = 20

This yields 3C = 24, so C = 8. When you plug that back in to C - L = 2, you see that L = 6, meaning that the total number of drinks is 8 + 6 = 14. Choice E is correct.

Why do you just multiply it by 2? Where does that come from and when is it appropriate to do that?

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

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Intern
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Joined: 26 Dec 2016
Posts: 29
Re: How many drinks?  [#permalink]

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New post 17 Jan 2018, 14:24
My bad, this is actually a sub-600 level question
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Joined: 02 Sep 2009
Posts: 48061
Re: How many drinks?  [#permalink]

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New post 17 Jan 2018, 20:54
rnz wrote:
Jim spent $60 purchasing lattes and coffees for his coworkers. If lattes cost $6 and coffees cost $3, and Jim purchased two more coffees than lattes, how many total drinks did he purchase?

A) 6
B) 8
C) 10
D) 12
E) 14

Official Solution:

In setting up a word problem like this, be sure to use meaningful variables. Here your variables are lattes (which you can call L) and coffees (which you can call C).

You can set up an equation to account for the $60 total: $6 times the number of lattes plus $3 times the number of coffees will account for the $60, so 6L + 3C = 60. You can then simplify by dividing everything by 3: 2L + C = 20.

You can also set up an equation based on the fact that there were 2 more coffees than lattes. The number of coffees, C, is equal to 2 plus the number of lattes, L, so:

C = 2 + L

With two equations and two variables, you can now solve. A quick way to do that is to subtract L from both sides of the second equation:

C - L = 2

If you then multiply both sides by 2, you have:

2C - 2L = 4


Which sets up for the elimination method when you stack and add the two equations:

2C - 2L = 4
C + 2L = 20

This yields 3C = 24, so C = 8. When you plug that back in to C - L = 2, you see that L = 6, meaning that the total number of drinks is 8 + 6 = 14. Choice E is correct.

Why do you just multiply it by 2? Where does that come from and when is it appropriate to do that?


Discussed here: jim-spent-60-purchasing-lattes-and-coffees-for-his-coworkers-if-latt-257834.html

Please search before posting and name topics properly. Check rule 3 here: rules-for-posting-please-read-this-before-posting-133935.html Thank you.

--== Message from GMAT Club Team ==--

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If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

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Re: How many drinks? &nbs [#permalink] 17 Jan 2018, 20:54
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