Question

Solve x + 3y = 9
3x − 3y = −13

Answer 1

Add the left hand sides together, and also add the right hand sides together

( x + 3y ) + [ 3x - 3y ] = ( 9 ) + [ -13 ]

Answer 2

Solve this equation for x

Answer 3

Plug this x you find into either of the original equations
and solve for y.

Answer 4

a) x + 3y = 9
b)3x − 3y = −13

Add the equations
4x = -4
x = -1

Substitute the value of x into equation "a"
a) -1 +3y = 9

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