3x^3y + 12xy − 9x^2y − 36y rewrite the expression completely factored. show the steps of your work.

Factor 3 out of 12:
3x^3y + 3 • 4xy - 9x^2y - 36y

Factor out 3 out of -9:
3x^3y + 3(4xy) + 3 • -3x^2y - 36y

Factor 3 out of -36:
3(x^3y) + 3(4x7) + 3(-3x^2y) + 3(-12)y

Factor 3 out of 3 (x^3y) + 3(-12y):
3(x^2y + 4xy) + 3(-3x^2y) + 3(-12y)

Factor 3 out of 3 (x^3y + 4xy) + 3(-3x^2y):
3(x^2y + 4xy - 3x^2y) + 3(-12y)

Factor 3 out of
3 (x^3y + 4xy - 3x^2y) + 3 (-12y):
3 (x^3y + 4xy - 3x^2y - 12y)