Question 141088
3x+4y=17
6y-2x=-20 


Rewrite this as 
3x+4y=17
-2x + 6y=-20 


To eliminate the x terms, you need to find a "common number" between the x coefficients.  This would be 6.  Multiply both sides of the first equation by 2 and the second equation by 3, and the x terms will subtract out!
2(3x+4y)=2(17)
3(-2x + 6y)=3(-20)


6x+8y=34
-6x +18y = -60


26y = -26 
y=-1


Solve for x by substituting the value of y =-1 into the first equation:

3x+4y=17
3x+4(-1) = 17
3x -4=17
3x=21
x=7


Check by substituting both values into the second equation:

-2x + 6y=-20 
-2(7) + 6(-1) =-20
-14-6=-20


This checks!!


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