12x-20y=108 3x+ky=27 what is k

Let's look at the second equation and try multiplying it by 4:

4 * (3x + ky) = 4 * 27

Which gives us:

12x + 4ky = 108

This looks almost exactly like the first equation except that instead of - 20y, there is 4ky. We could try making them equal to each other and solving for k:

-20y = 4ky

-20 = 4k

k = - 5

Then, the answer is k = - 5.