First off, 6x = x is impossible. 6 of something (x) does not equal 1 of the same something (x). So for that question, there are no possible answers for x.
2x-x = x has an infinite number of answers. 2x-x = x when simplified is x = x. So, you could plug anything in for x, and it would always equal... guess what... whatever you plugged in for x. x could be 12, -16, pi, 3.068361, 32%, in 2x-x = x there are an infinite number of answers as to what x is because x always equals x.
