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

8 Answers

jlcannad's profile pic

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

Posted on

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



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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malkaam | Student, Undergraduate | (Level 1) Valedictorian

Posted on




In order to find the value of x we must first find the value of y, to do that let us first consider equation (i): y-3=7


y-3+3=7+3    (adding 3 on both sides)


Then, we input the value of y in equation (ii): x+3y=6


Input the value of y in this equation i.e 10


x+30-30=6-30     (subtract 30 from both sides)

x= -24 Answer.

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jess1999 | Student, Grade 9 | (Level 1) Valedictorian

Posted on

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

First let's find what " y " equals

y - 3 = 7 add 3 on both sides

By adding, you should get

y = 10 which is what " y " equals 

Now plug 10 into the equation

x + 3 ( 10 ) = 6 multiply 3 with 10

By multiplying,  you should get

x + 30 = 6 now subtract 30 on both sides

By subtracting, your equation should look like

x = -24 which Is your answer

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acompanioninthetardis | Student, Undergraduate | (Level 1) Valedictorian

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

we need ot get the unkown variables by themselves, and usually you start with the equation that only has one unknown variable, wheich would be y-3=7

you add three to both sides so the -3 goes away leaving you with the value of y


then you plug this value into the other equation x+3y=6

to give you X+ 3(10) = 6


then you do the same thing, you try to get the 30 onto the right side by subtracting 30 from both sides so it gives you the value of X

X= -24

atyourservice's profile pic

atyourservice | Student, Grade 11 | (Level 3) Valedictorian

Posted on

 y-3=7 and x+3y=6 then x=

y - 3 = 7

   +3   +3


plug in the number in the second problem



  -30   -30

x= -24

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Wiggin42 | Student, Undergraduate | (Level 2) Valedictorian

Posted on

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