Simplify the expression 6x x 2x^3 x 3x^2y^2/3x^3 x x^4y.

I'm confused. The only thing I did was simplify 3x^2y^2/3x^3 to x^1y^2. I need help with the problem.

You seem to be using "x" both as a variable and as the symbol for multiplication. We prefer to use * for multiplication here, to avoid confusion.

I assume you want to simplify
6x*2x^3 * 3x^2*y^2/(3x^3*x^4*y).
(This assumes that your x^4y at the end belongs in the denominator).
Rewrite it by adding repeated exponents:
36 x^6*y^2/(3x^7*y)
= 12 x/y

The simplification you wrote is wrong.
3x^2y^2/3x^3 = y^2*x^-1 = y^2/x