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If 3y + 5 = 7x, then 21y – 49x =
[#permalink]
25 Feb 2021, 05:19
25 Feb 2021, 05:19
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Question Stats:
100% (00:41) correct
0% (00:00) wrong based on 27 sessions
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If 3y + 5 = 7x, then 21y – 49x =
(A) –40
(B) –35
(C) –10
(D) 0
(E) 15
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
(A) –40
(B) –35
(C) –10
(D) 0
(E) 15
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: If 3y + 5 = 7x, then 21y – 49x =
[#permalink]
25 Feb 2021, 07:04
25 Feb 2021, 07:04
Carcass wrote:
If 3y + 5 = 7x, then 21y – 49x =
(A) –40
(B) –35
(C) –10
(D) 0
(E) 15
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
(A) –40
(B) –35
(C) –10
(D) 0
(E) 15
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
Given: 3y + 5 = 7x
Subtract 5 from both sides to get: 3y = 7x - 5
Subtract 7x from both sides to get: 3y - 7x = -5
ASIDE: Why did I rewrite the given equation like that?
Well, since we want to find the value of 21y – 49x, I thought it might be useful to rewrite the given equation in the same form (something times y - something times x)
We want to find the value of 21y – 49x
Notice that we can factor this expression to get: 21y – 49x = 7(3y - 7x)
= 7(-5) [since we already determined that 3y - 7x = -5]
= -35
Answer: B
Cheers,
Brent
gmatclubot
Re: If 3y + 5 = 7x, then 21y – 49x = [#permalink]
25 Feb 2021, 07:04
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