Substitituion method, what would be X and Y? -

The equation is: 

3X - 8Y = 20

-5X - Y = 19

Solution:

-5x - y = 19

-y = 19 + 5x -- (-y = 19 + 5x) -1 

                       y = 19 - 5x

Finding X using Y

3x - 8y = 20

3x - 8(19-5x) = 20

3x - 152 + 40x = 20

43x - 152 = 20

43x = 20 + 152

43x = 172 (divide both sides by 43)

x = 4

Finding Y using X

Y= 19 - 5x

  = 19 - 5(4)

  = 19 - 20

 Y = -1

Checking:

3(4) - 8(-1) = 20

12 + 8 = 20

20 = 20

-5(4) - (-1) = 19

-20 + 1 = 19

19 = 19

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