Question

x=10+y
12x-9y=9

Answer 1

substitution or elimination

Answer 2

both\

Answer 3

substitution is easier here because: x=10+y

we know x so just put it in the 2nd equation like so:

12(10 + y) - 9y = 9

do you know what's next???

Answer 4

or elimination is
manipulating one of the equations so we can get rid of one of the variables :

x-y = 10 rearranging first and then mult by -12

gives -12x +12y = -120 then add the equations together

-12x +12y = -120
12x -9y = 9

3y = -111

Answer 5

Ok first you want to plug in x, which is 10+y, into 12x-9y=9. There fore you get 12(10+y)-9y=9. Simplify you get 120+12y-9y=9, now simplify it again to 3y=-111 divide 3 to -111 to get y by itself to get (y=-111/3). Now to find x plug in y into the x function, which is x=10+y, you'll get x=10+(-111/3), you should get x=-27.

So all in all, y= -111/3 and x=-27