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If y-3=7 and x+3y=6 then x=?Show your work.

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loveetteee | Student | eNotes Newbie

Posted May 28, 2009 at 5:03 AM via web

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If y-3=7 and x+3y=6 then x=?

Show your work.

5 Answers | Add Yours

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jlcannad | High School Teacher | (Level 2) Assistant Educator

Posted May 28, 2009 at 5:10 AM (Answer #1)

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I can't answer x+3y=6 right now.  I have two variables (x and Y) so I'm stuck.

So, I turn to my other equation.  y-3=7.  If I add three to each side of the equation, I get y=10.

Now that I know y=10, I can put the number 10 in every place there was a "y."  So, the second equation looks like this...

x+3y=6

x+3(10)=6

x+30=6      So I subtract 30 from each side.

x=-24

 

I then check myself by putting all my numbers back into the original equations.

10-3=7 and -24+3(10)=6

Yep, that works.

 

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emplay | Student , Grade 11 | eNotes Newbie

Posted May 28, 2009 at 5:13 AM (Answer #2)

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Well

x+3y=6   and y-3=7

(+3)y-3=7(+3)

y=10

 

x+3(10)=6

x+30=6

x= -24

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Jyotsana | Student , Grade 10 | eNoter

Posted February 7, 2014 at 2:11 AM (Answer #3)

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y-3=7

y-3+3=7+3

y=10

x+3y=6

x+3(10)=6

x+30=6

x+30-30=6-30

x=-24

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Wiggin42 | Student , Grade 12 | eNoter

Posted March 23, 2014 at 4:16 PM (Answer #4)

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If y-3=7 and x+3y=6 then x=?

First solve for y because we have enough information for that. 

y = 3 + 7 = 10

plug into the other equation: 

x + 3(10) = 6

x + 30 = 6

x = 6 - 30 = -24

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atyourservice | Student , Grade 10 | eNoter

Posted April 16, 2014 at 6:10 PM (Answer #5)

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 y-3=7 and x+3y=6 then x=

y - 3 = 7

   +3   +3

y=10

plug in the number in the second problem

x+3(10)=6

x+30=6

  -30   -30

x= -24

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