help ive been struggling with this for awhile

You are given the expression 36x4y3 − 16x3y.

Part A: Find a common factor for the expression that has a coefficient other than 1 and that contains at least one variable. (1 point)

Part B: Explain how you found the common factor. (1 point)

Part C: Rewrite the expression using the common factor you found in Part A. Show every step of your work