Question

What happens if 0x is your answer?

Answer 1

it depends x cant equal zero unless your teacher says it can which most of the time it cant so therefore no it cant.

Answer 2

0 times anything is 0. 4 times 0 =0. tree times 0 = 0. Cat times 0=0. Therefore, 0x=0.

If it's part of an equation:
0x+4y= 4y. The 0 is technically there, but depending on what you're doing, you don't need to denote it. 

I think this might help you. If you're talking about 0x in the context of a specific function or something, please clarify.