Question

Solve the system of linear equations by elimination. 3x+3=3y and 2x−6y=2

Answer 1

3x + 3 = 3y         < -- make this 3x - 3y = -3
2x - 6y = 2

multiply by 2 on the first equation
6x - 6y = -6
2x - 6y = 2           
subtract them

4x = -8
x = -2


substitute x = -2 into any of the equation
2x - 6y = 2
2(-2) - 6y = 2
-4 - 6y = 2
-6y = 6
y = -1

So the answer is 
(-2 , -1)

Answer 2

Put both equation in standard form Ax + By = C
3x - 3y = -3  ← -2×(3x - 3y = -3)               → - 6x + 6y = 6
2x - 6y = 2 → now y-terms are opposites        2x - 6y = 2
add                                                                 -4x = 8
divide by -4                                                        x = -2
plug x value into one of the equations 3(-2) + 3 = 3y and solve
                                                             -6 + 3 = 3y
                                                                  -3  = 3y
                                                                   -1 = y
Answer: (-2, -1)