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Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
If 6x - 7y = 11 and -5y = 13 + 5x, what is the sum of x
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04 Aug 2020, 06:10
04 Aug 2020, 06:10
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Question Stats:
77% (02:07) correct
22% (01:57) wrong based on 27 sessions
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If 6x - 7y = 11 and -5y = 13 + 5x, what is the sum of x and y?
(A) -5.2
(B) -2.6
(C) -1.3
(D) 1.3
(E) 2.6
(A) -5.2
(B) -2.6
(C) -1.3
(D) 1.3
(E) 2.6
Re: If 6x - 7y = 11 and -5y = 13 + 5x, what is the sum of x
[#permalink]
04 Aug 2020, 07:06
04 Aug 2020, 07:06
Given,
6x - 7y = 11 and -5x - 5y = 13
Add the two equations, we get
x-12y=24
x = 24 + 12y
Put in eq 2:
-5x - 5y = 13
-5 (24+12y) - 5y = 13
-133 = 65 y
y = -2.04
put in other equation for x
x = 24 + 12y
x = 24 + 12(-2.04)
x = -0.55
so x + y = -2.04 - 0.55
= -2.6 (approx) option B
6x - 7y = 11 and -5x - 5y = 13
Add the two equations, we get
x-12y=24
x = 24 + 12y
Put in eq 2:
-5x - 5y = 13
-5 (24+12y) - 5y = 13
-133 = 65 y
y = -2.04
put in other equation for x
x = 24 + 12y
x = 24 + 12(-2.04)
x = -0.55
so x + y = -2.04 - 0.55
= -2.6 (approx) option B
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: If 6x - 7y = 11 and -5y = 13 + 5x, what is the sum of x
[#permalink]
04 Aug 2020, 07:25
04 Aug 2020, 07:25
Nice work, @Farina
Can you find a different (faster) solution?
Cheers,
Brent
Can you find a different (faster) solution?
Cheers,
Brent
