I'm assuming that this is :
[X-3 ] / X = [ X-3 ] / [X-6] if so .....cross - multiply
[x -3] [x - 6] = [x] [x - 3] simplify
x^2 - 9x + 18 = x^2 - 3x subtract x^2 from both sides, add 3x to both sides
-6x + 18 = 0
-6x = - 18 divide both sides by -6
x = 3
