How to eliminate(or graph) -6x=-3y-27 5x=-2y+18 and some others

Question

Recently I've only been finding videos/lessons that show how to eliminate using the general x+y=5

                                                                                                                                   x+y=5

 But i have no idea what to do when a problem asks   y=x+5

                                                                             y=x+5

Or when x=y+5 for example.Please help,you don't have to solve them all if you don't want to.

             x=y+5

 

1.How can i eliminate this

                                                  -6=-3y-27

                                                  5x=-27+28

 

2.How can i eliminate and/or graph this

                                                   

                                                 3x-3y=6

                                                 1y=x+2

                                                 3        3

3.How can i eliminate and/or graph this

                                                 3x-y=0

                                                 2y=6x+12

Answer 1

For the second question:

3x -3y = 6

1/3 y = x + 2/3  This will become if you subtract x on both sides of the equation: -x + 1/3 y = 2/3

 

If you multiply this second equation by 3 you will get: -3x + y = 2

 

Now let's line up both equations:

3x - 3y = 6

-3x + y = 2

 

You can eliminate the 3x and you will get -2y = 8; then dividing both sides by -2, the answer will be y = -4.

 

Substitution of y = -4 in the second equation will result in -3x + (-4) = 2; therefore -3x = 6 and then x = -2.

 

Check your answer by substitution in one of the equations.

 

For the third one, you follow the same logic.